Design and Evaluation of ZD06519, a Novel Camptothecin Payload for Antibody Drug Conjugates

In recent years, the field of antibody drug conjugates (ADC) has seen a resurgence, largely driven by the clinical benefit observed in patients treated with ADCs incorporating camptothecin-based topoisomerase I inhibitor payloads. Herein, we present the development of a novel camptothecin ZD06519 (FD1), which has been specifically designed for its application as an ADC payload. A panel of camptothecin analogs with different substituents at the C-7 and C-10 positions of the camptothecin core was prepared and tested in vitro. Selected compounds spanning a range of potency and hydrophilicity were elaborated into drug-linkers, conjugated to trastuzumab, and evaluated in vitro and in vivo. ZD06519 was selected on the basis of its favorable properties as a free molecule and as an antibody conjugate, which include moderate free payload potency (∼1 nmol/L), low hydrophobicity, strong bystander activity, robust plasma stability, and high-monomeric ADC content. When conjugated to different antibodies using a clinically validated MC-GGFG-based linker, ZD06519 demonstrated impressive efficacy in multiple cell line-derived xenograft models and noteworthy tolerability in healthy mice, rats, and non-human primates.

Developing a Nanopore Sequencing Workflow for Protein Engineering Applications

Sequencing plays a critical role in protein engineering, where the genetic information encoding for a desired mutation can be identified. We evaluated the performance of two commercially available NGS technologies (Illumina NGS and nanopore sequencing) on the available mutant libraries that were either previously constructed for other protein engineering projects or constructed in-house for this study. The sequencing results from Illumina sequencing indicated that a substantial proportion of the reads exhibited strand exchange, which mixed information of different mutants. When nanopore sequencing was used, the occurrence of strand exchange was substantially reduced compared with that of Illumina sequencing. We then developed a new library preparation workflow for nanopore sequencing and were successful in further reducing the incidence of strand exchange. The optimized workflow was successfully used to aid selection of improved alcohol dehydrogenase mutants in cells where their activities were coupled with the cell growth rate. The workflow quantified the enrichment fold change of most mutants in the library (size = 1728) in the growth-based selection passaging. A mutant that was >500% more active than its parent variant was identified based on the fold change data but not with the absolute abundance data (random sampling of the passaged cells), highlighting the usefulness of this rapid and affordable sequencing workflow in protein engineering.

Abstract 2641: ZW191, a novel FRa-targeting antibody drug conjugate bearing a topoisomerase 1 inhibitor payload

Background: Folate Receptor alpha (FRa) is a validated cell surface cancer target that is prevalently expressed in multiple cancers with high unmet need, including ovarian cancer and other gynecological cancers, while exhibiting minimal expression in normal tissues. Due to FRa’s favorable expression profile, multiple antibody-drug conjugates (ADCs) are being explored in this setting. Here we present the preclinical characterization of a new anti-FRa ADC, ZW191. ZW191 is an antibody drug conjugate (ADC) comprised of a humanized IgG1 antibody conjugated to a novel camptothecin-based topoisomerase 1 inhibitor payload, ZD06519, via a maleimidocaproyl (MC) anchor and a glycyl glycyl phenylalanyl glycine (GGFG)-aminomethyl (AM) cleavable linker at a drug-to-antibody ratio (DAR) of 8.

Materials and Methods: The novel antibody and drug-linker components of ZW191 were generated, characterized, and optimally integrated. The apparent binding affinity and cellular internalization of the ZW191 antibody, and the intracellular concentration of the released camptothecin payload, ZD06519, were determined in FRa-expressing cells. Additionally, the binding specificity of the ZW191 antibody was determined using a cell microarray technology to test for binding against over 6,000 full length proteins that are individually over-expressed in human cells. Tumor spheroid cancer cell cultures were utilized to determine the cytotoxicity of ZW191 and the ability of ZW191 to penetrate the layers of the three-dimensional (3D) spheroid. The bystander activity of ZW191 was assessed using antigen positive and negative co-culture experiments. The anti-tumor activity of ZW191 was evaluated in a panel of cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) ovarian cancer models spanning a range of FRa expression. ZW191 was evaluated in toxicology and pharmacokinetic (PK) studies performed in rodents and non-human primates (NHP).

Results: The antibody component of ZW191 features a favorable binding profile with strong and exclusive binding to FRa, and drives superior tumor spheroid penetration, cellular internalization, and payload delivery compared to FRa targeted antibodies used in other ADCs. ZW191 demonstrates potent activity in FRa expressing 3D tumor spheroid cultures and effective bystander activity. In a panel of CDX and PDX models representing a range of FRa expression, ZW191 demonstrates compelling anti-tumor activity at exposures that are estimated to be readily achievable in the clinic. ZW191 was tolerated up to 200 mg/kg in a two-dose rat study and at 30 mg/kg in a two-dose NHP study, with favorable PK. The promising efficacy, tolerability, and PK supports the potential of ZW191 as a novel therapeutic agent that may help address unmet need in patients with high and low FRa-expressing cancers.

Citation Format: Sam Lawn, Andrea Hernandez Rojas, Raffaele Colombo, Dayananda Siddappa, Jodi Wong, Kaylee Wu, Vincent Fung, Dunja Urosev, Luying Yang, Jamie R. Rich, Stuart D. Barnscher. ZW191, a novel FRa-targeting antibody drug conjugate bearing a topoisomerase 1 inhibitor payload [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2641.

Lack of avoidance of the fungal entomopathogen, Metarhizium brunneum, by male Agriotes obscurus beetles

Fungal entomopathogens can greatly reduce the fitness of their hosts, and it is therefore expected that susceptible insects will be selected to avoid exposure to pathogens. Metarhizium brunneum is a fungal pathogen that can infect Agriotes obscurus, which in its larval form is a destructive agricultural pest and is repelled by the presence of M. brunneum conidia. Due to the subterranean nature of larval A. obscurus, recent research has focused on targeting adult A. obscurus with M. brunneum. No-choice and choice behavioural assays were conducted to determine if male adult A. obscurus avoid M. brunneum mycosed cadavers, or conidia applied to either food or soil. To further investigate the response of A. obscurus beetles to conspecific cadavers, the movement and behaviour of beetles placed at the centre of a semi-circular arrangement of mycosed or control cadavers was examined using motion tracking software. We found little evidence to suggest that A. obscurus male beetles avoid M. brunneum conidia or mycosed conspecific cadavers or alter their behaviour in their presence.

Producing aromatic amino acid from corn husk by using polyols as intermediates

Agricultural biomass remains as one of the commonly found waste on Earth. Although valorisation of these wastes has been studied in detail, the fermentation-based processes still need improvement due to the high cost of hydrolysing enzymes, and the presence of growth inhibitors which constrains the fermentation to produce high-value products. To address these challenges, we developed an integrated process in this study combining abiotic- and bio-catalysis to produce l-tyrosine from corn husk. The first step involved a one-pot hydrolytic hydrogenation tandem reaction without the use of the expensive enzymes, which yielded a mixture of polyols and sugars. Without any purification, these crude hydrolysates can be almost completely utilized by an engineered Escherichia coli strain, which did not exhibit any growth inhibition. The strain produced 0.44 g/L l-tyrosine from 10 g/L crude corn husk hydrolysates, demonstrating the feasibility of converting agricultural biomass into a valuable aromatic amino acid via an integrated process.

Abstract 61: Zymelink drug conjugate platform: redefining the therapeutic window for ADCs

Antibody drug conjugates (ADCs) combine the specificity of monoclonal antibodies with potent antineoplastic small molecules, and promise efficacy without the systemic toxicity of chemotherapy. Despite this tremendous potential, most clinical ADCs have failed to provide sufficient therapeutic benefit before the onset of off-target dose-limiting platform toxicities.

Here we report the development of proprietary protease cleavable N-acyl sulfonamide linked hemiasterlin and auristatin payloads, Zymelink, that allow the generation of an efficacious ADC platform with improved tolerability. Both Zymelink drug-linkers were conjugated via maleimides to endogenous cysteines. As Zymelink drug-linkers are more polar than maleimide valine citrulline monomethyl auristatin E drug-linker, the resulting ADCs can be produced with potential advantages in PK, efficacy and safety. The resulting ADCs exhibit potent in vitro cytotoxicity. A trastuzumab-based ADC prepared with Zymelink drug-linker and demonstrated at least equivalent efficacy compared to a trastuzumab-based ADC prepared with MMAE, promoting durable complete regressions in a patient-derived xenograft model.

Zymelink hemiasterlin and auristatin ADCs were tolerated at 5-6 fold higher doses compared to a MMAE ADC in cynomolgus monkeys. The maximum tolerated dose of the MMAE ADC was just 3 mg/kg based on severe neutropenia. Zymelink hemiasterlin ADC was tolerated at 15 mg/kg with no evidence of neutropenia or elevations in transaminases. Zymelink auristatin ADC was tolerated at 18 mg/kg based on increased levels of transaminases at 24 mg/kg. Moreover, Zymelink ADCs exhibited greater serum exposure at equivalent doses. These results suggest Zymelink ADCs have a greatly expanded therapeutic window compared to MMAE conjugates.

Citation Format: Stuart Barnscher, John Babcook, Jamie Rich, Geoff Winters, Graham Garnett, Andrea Hernandez, Vincent Fung, Kevin Yin, Kevin Hamblett, Rupert Davies. Zymelink drug conjugate platform: redefining the therapeutic window for ADCs [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 61. doi:10.1158/1538-7445.AM2017-61

Burkitt lymphoma expresses oncofetal chondroitin sulfate without being a reservoir for placental malaria sequestration

Burkitt lymphoma (BL) is a malignant disease, which is frequently found in areas with holoendemic Plasmodium falciparum malaria. We have previously found that the VAR2CSA protein is present on malaria-infected erythrocytes and facilitates a highly specific binding to the placenta. ofCS is absent in other non-malignant tissues and thus VAR2CSA generally facilitates parasite sequestration and accumulation in pregnant women. In this study, we show that the specific receptor for VAR2CSA, the oncofetal chondroitin sulfate (ofCS), is likewise present in BL tissue and cell lines. We therefore explored whether ofCS in BL could act as anchor site for VAR2CSA-expressing infected erythrocytes. In contrast to the placenta, we found no evidence of in vivo sequestering of infected erythrocytes in the BL tissue. Furthermore, we found VAR2CSA-specific antibody titers in children with endemic BL to be lower than in control children from the same malaria endemic region. The abundant presence of ofCS in BL tissue and the absence of ofCS in non-malignant tissue encouraged us to examine whether recombinant VAR2CSA could be used to target BL. We confirmed the binding of VAR2CSA to BL-derived cells and showed that a VAR2CSA drug conjugate efficiently killed the BL-derived cell lines in vitro. These results identify ofCS as a novel therapeutic BL target and highlight how VAR2CSA could be used as a tool for the discovery of novel approaches for directing BL therapy.

Regulatory verification on safe use of cytotoxic drugs in veterinary clinics and animal hospitals

BACKGROUND

Veterinarians are increasingly being asked to provide chemotherapy for veterinary patients. However, chemotherapy agents have cytotoxic effects that can pose a health risk to workers from exposure. There are no published studies examining cytotoxic drug (CTD) contamination in veterinary practices in Australia.

METHODS

CTD use at 13 veterinary clinics and animal hospitals across New South Wales (NSW) was verified for compliance with Work, Health and Safety (WHS) legislation on the effectiveness of exposure control measures. Surface swab sampling was performed to detect the restricted carcinogen cyclophosphamide and seven other CTD. A total of 73 surface swab samples were collected from nine locations associated with CTD delivery, storage, treatment and waste disposal at four veterinary practices, with repeat sampling at two veterinary practices.

RESULTS

Compliance with WHS legislation for systematic chemical management, including procedures for safe use of carcinogens, in veterinary practices was high: 4 of the 10 key clauses in WHS chemical management were complied with at all 13 verified workplaces. Surface contamination was detected in three locations, with levels of CTD contaminants ranging from 3.54 to 89 ng per sample.

DISCUSSION

Results showed that, in general, there were safe systems in place to work with CTD in the veterinary practices that were verified in NSW. Areas for improvement were mainly in administrative measures related to hazardous chemical management. Particular attention should be given to raising awareness of the intrinsic hazards of CTD, through training and hazard information provision to staff.

A retrospective comparative study with historical control to determine the effectiveness of platelet-rich plasma as part of nonoperative treatment of acute achilles tendon rupture

PURPOSE

The aim of this study was to evaluate the effectiveness of platelet-rich plasma (PRP) in the nonoperative treatment of acute Achilles tendon rupture.

METHODS

This was a comparative study that included a prospective cohort and a historical control group. The control group was formed from a randomized trial in which one arm of the trial underwent nonoperative treatment, including accelerated functional rehabilitation after acute Achilles tendon rupture identical to that performed in the prospective treatment group. Patients in the prospective group were recruited consecutively and were administered 2 injections of PRP during the first 2 weeks after the injury. The primary outcome was isokinetic plantar flexion strength at 1 and 2 years after injury. Secondary outcomes included range of motion (ROM), calf circumference, and Leppilahti score. The ankle-hindfoot scale (American Orthopedic Functional Ankle Scale [AOFAS]) was administered to patients who received the PRP injection in the prospective group but was not measured for the historical group.

RESULTS

A total of 73 patients participated in the prospective PRP study group and were compared with a retrospective control group of 72 patients from a previous randomized controlled trial (RCT). The mean difference between groups in isokinetic plantar flexion strength (injured/uninjured) at 1 year after injury was -4.3% (95% confidence interval [CI], -15.9 to 7.3; P = .5) and 2.4% (95% CI, -8.6 to 13.5; P = .7) at 30°/s and 60°/s, respectively. Results at 2 years after injury were -3.1% (95% CI, -13.5 to 7.2; P = .6) and 4.8% (95% CI, -3.5 to 13.1; P = .3) at 30°/s and 60°/s, respectively. All secondary outcomes were also not statistically different.

CONCLUSIONS

The results of this study suggest that there is no measurable clinical benefit to the addition of PRP to the treatment regimen for nonoperatively treated acute Achilles tendon rupture.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Clinical practice guideline: CYP2D6 genotyping for safe and efficacious codeine therapy

This guideline is intended to provide a basis for informed decision-making regarding genetic testing to identify those individuals who will not benefit from codeine therapy, as well as those who are at an increased risk for codeine-induced toxicity. This guideline addresses the following key questions: 1) Should genetic testing for CYP2D6 be performed in patients prior to the initiation of codeine therapy? 2) How should patients with an indication for codeine therapy be managed based on their genotyping results for CYP2D6?

RE-EVALUATION OF THE CORRECTION FACTOR FOR ETHANOL IN THE CALCULATION OF THE OSMOLAL GAP

Background/objectives: It is well-known that ethanol (EtOH) demonstrates non-ideal solute behaviour in plasma. This is reflected by its larger than expected contribution to the plasma osmolality. Published multiplicative correction factors for the EtOH contribution range from 1.20 to 1.25. The objective of this study is to determine an optimal correction factor specific to the instrumentation at Vancouver General (VGH) and St. Paul's (SPH) Hospitals. Methods: Laboratory data from patients presenting to the two respective emergency department between August 01, 2007 and November 30, 2008 were extracted from the Sunset database. Plasma sodium, urea, glucose, and EtOH were measured using the two high-volume chemistry analyzers employed at the sites: the Siemens (previously Dade) RXL (VGH) and the Siemens (previously Bayer) Advia 1650 (SPH). Plasma osmolality was measured by freezing-point depression and calculated (excluding the EtOH contribution) using the following standard formula (in SI units): 2 [Na] + [Urea] + [Glucose]. Patients without EtOH data or who had undetectable EtOH were excluded as were patients with methanol or ethylene glycol present. Standard regression statistics were employed. Results: Twelve hundred and fifty-three patient samples (n=823 from SPH and n=430 from VGH) were included. Empirical correction factor m, satisfying, Osmol gap (mmol/kg) =m[EtOH] (mmol/L) was consistently found to be 1.15 for VGH, SPH and both combined. Conclusions: The correction factor of 1.15 for ethanol from the current study appears to be more representative and reliable. Further studies to evaluate its validity in other hospital sites as well as its utility in screening patients with known toxic alcohol ingestion will be warranted.

Myoclonus-dystonia: significance of large SGCE deletions

Myoclonus-dystonia (M-D) is an autosomal-dominant movement disorder caused by mutations in SGCE. We investigated the frequency and type of SGCE mutations with emphasis on gene dosage alterations and explored the associated phenotypes. We tested 35 M-D index patients by multiplex ligation-dependent probe amplification (MLPA) and genomic sequencing. Mutations were found in 26% (9/35) of the cases, all but three with definite M-D. Two heterozygous deletions of the entire SGCE gene and flanking DNA and a heterozygous deletion of exon 2 only were detected, accounting for 33% (3/9) of the mutations found. Both large deletions contained COL1A2 and were additionally associated with joint problems. Further, we discovered one novel small deletion (c.771_772delAT, p.C258X) and four recurrent point mutations (c.289C>T, p.R97X; c.304C>T, p.R102X; c.709C>T, p.R237X; c.1114C>T, p.R372X). A Medline search identified 22 articles on SGCE mutational screening. Sixty-four unrelated M-D patients were described with 41 different mutations. No genotype-phenotype association was found, except in patients with deletions encompassing additional genes. In conclusion, a rigorous clinical preselection of patients and careful accounting for non-motor signs should precede mutational tests. Gene dosage studies should be included in routine SGCE genetic testing.

Oxidative stress potentiates BACE1 gene expression and Abeta generation

Alzheimer's Disease (AD) is the most common neurodegenerative disorder leading to dementia and its prevalence increases with age. The pathological features of AD are characterized by the beta-amyloid protein (A(beta)) deposits in the core of neuritic plaques and abnormal neurofibrillary tangles in the brain of AD patients. BACE1 is the major beta-secretase to cleave the beta-amyloid precursor protein (APP) to generate A(beta). Oxidative stress has been shown to affect A(beta) generation in the AD pathogenesis and the mechanism of such effect is unknown. In this report we generated a novel promoterless enhanced green fluorescent protein (EGFP) reporter gene cloning vector and cloned a 1.9-kb BACE1 gene promoter fragment in this vector. The BACE1 promoter fragment can efficiently activate EGFP or luciferase gene transcription. Oxidative stress induced by hydrogen peroxide resulted in significant increase in the BACE1 promoter activity. Furthermore, hydrogen peroxide treatment facilitated beta-secretase activity and A(beta) generation. Thus, upregulation of BACE1 transcription by oxidative stress may contribute to the pathogenesis of Alzheimer's disease.

Structured data entry of clinical information for documentation and data collection

Routine databases containing large amounts of clinical data represent a tremendous opportunity for the evaluation of health care practices and outcomes. However, data collected for administrative purposes has limitations in content, accuracy and completeness. Routine entry of clinical information directly into clinical information systems by care providers is one strategy to address this problem. We developed a structured data entry method, the Clinical Data Framework (CDF), which has been used to support the capture of clinical information by clinicians in the normal process of care delivery. A study of the CDF over a two month period showed that it improved the accuracy of completeness of data collection over a coding method which was based on selection of ICD-9-CM codes.

Medical informatics--the state of the art in the Hospital Authority

Since its inception in 1990, the Hospital Authority (HA) has strongly supported the development and implementation of information systems both to improve the delivery of care and to make better information available to managers. This paper summarizes the progress to date and discusses current and future developments. Following the first two phases of the HA information technology strategy the basic infrastructural elements were laid in place. These included the foundation administrative and financial systems and databases; establishment of a wide area network linking all hospitals and clinics together; laboratory, radiology and pharmacy systems with access to results in the ward. A major push into clinical systems began in 1994 with the clinical management system (CMS), which established a clinical workstation for use in both ward and ambulatory settings. The CMS is now running at all major hospitals, and provides single logon access to almost all the electronically collected clinical data in the HA. The next phase of development is focussed on further support for clinical activities in the CMS. Key elements include the longitudinal electronic patient record (ePR), clinical order entry, generic support for clinical reports, broadening the scope to include allied health and the rehabilitative phase, clinical decision support, an improved clinical documentation framework, sharing of clinical information with other health care providers and a comprehensive data repository for analysis and reporting purposes.

Fast, global, and entrepreneurial: supply chain management, Hong Kong style. An interview with Victor Fung. Interview by Joan Magretta

Li & Fung, Hong Kong's largest export trading company, has been an innovator in supply chain management--a topic of increasing importance to many senior executives. In this interview, chairman Victor Fung explains both the philosophy behind supply chain management and the specific practices that Li & Fung has developed to reduce costs and lead times, allowing its customers to buy "closer to the market." Li & Fung has been a pioneer in "dispersed manufacturing." It performs the higher-value-added tasks such as design and quality control in Hong Kong, and outsources the lower-value-added tasks to the best possible locations around the world. The result is something new: a truly global product. To produce a garment, for example, the company might purchase yarn from Korea that will be woven and dyed in Taiwan, then shipped to Thailand for final assembly, where it will be matched with zippers from a Japanese company. For every order, the goal is to customize the value chain to meet the customer's specific needs. To be run effectively, Victor Fung maintains, trading companies have to be small and entrepreneurial. He describes the organizational approaches that keep the company that way despite its growing size and geographic scope: its organization around small, customer-focused units; its incentives and compensation structure; and its use of venture capital as a vehicle for business development. As Asia's economic crisis continues, chairman Fung sees a new model of companies emerging--companies that are, like Li & Fung, narrowly focused and professionally managed.

Brainstem myoclonus in a patient with non-dopa-responsive parkinsonism

In the few reports where electrophysiologic techniques have been used to characterise stimulus-sensitive myoclonus in the setting of a parkinsonian syndrome, the origin of the myoclonus has usually been found to be cortical. We describe a patient with parkinsonism unresponsive to levodopa who had myoclonus that was both spontaneous and induced by somatosensory stimuli. In addition, autonomic symptoms and a marked sleep disturbance were present early in his illness. Results of electrophysiologic investigations including electromyography (EMG) studies, routine electroencephalography (EEG) recording, jerked locked back-averaging of EEG, and somatosensory evoked potentials were consistent with a brainstem origin for the myoclonic jerks. Following ipsilateral digital and supraorbital electrical stimulation, the earliest muscle activation occurred in the trapezius. An all-night sleep study showed frequent myoclonic jerks during sleep and markedly abnormal sleep architecture. We believe that this patient's myoclonus was related to pathologic changes in brainstem reticular nuclei that occurred as part of his disease process. To our knowledge, brainstem myoclonus has not been described as a feature of parkinsonian syndromes.

The development of medical record services in Hong Kong public hospitals

Medical record service in Hong Kong public hospitals have been developing at different levels. Since 1992, various improvements in medical record services have been carried out in public hospitals, e.g. professional management, record storage, organized medical records, computerization, completion of discharge summaries, and the introduction of a more precise coding system. The aim of the reform is to provide timely, accurate, organized and meaningful clinical information for end-users. Evolving from this reform, work has been started on developing Patient Related Groups and Specialty Clinical Information Systems.

Cloning of a T cell growth factor that interacts with the beta chain of the interleukin-2 receptor

A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary DNA clone encoding this new T cell growth factor was isolated. The cytokine, designated interleukin-15 (IL-15), is produced by a wide variety of cells and tissues and shares many biological properties with IL-2. Monoclonal antibodies to the beta chain of the IL-2 receptor inhibited the biological activity of IL-15, and IL-15 competed for binding with IL-2, indicating that IL-15 uses components of the IL-2 receptor.