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Claudin 18.2 (CLDN18.2) is aberrantly overexpressed in gastric cancer, pancreatic adenocarcinomas, and a fraction of non-small cell lung cancer. Its tumor specificity allows CLDN18.2 to be an attractive target for developing biotherapeutics for the treatment of gastric and pancreatic cancers. DR30303 is a humanized ant-CLDN18.2 heavy chain antibody Fc fusion protein (VHH-Fc) generated via Doer Biologics’ proprietary SMART-VHHBody platform. DR30303 exhibits strong and highly selective binding to CLDN18.2, but not its close splicing variant CLDN18.1. In addition, it exhibits enhanced ADCC activity as a result of Fc engineering and low immunogenicity risk validated via in-silico T-cell epitope predictor. Its smaller size (78 kDa vs 150 kDa for conventional full-length IgG) allows DR30303 to penetrate solid tumors faster and deeper, resulting in a strong competitive advantage and differentiation compared with other anti-CLDN18.2 antibodies in the market. Single-agent therapeutic potency of DR30303 was demonstrated in various gastric and pancreatic cell-derived xenograft (CDX) mouse models with a minimum effective dose of 0.3 mg/kg dose of DR30303 led to TGI≥90%, which is significantly more potent (p Citation Format: Yongliang Fang, Gaofeng Yao, Weixiang Zhong, Wenwen Duan, Zhenxing Zhou, Xiaofang Wen, Yonglu Chen, Jingjin Fang, Yongwei Wang, Weiqin Jiang, Junfang Xu, Yanshan Huang. DR30303, a SMART-VHHBody powered anti-CLDN18.2 VHH-Fc with enhanced ADCC activity for the treatment of gastric and pancreatic cancers [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 2857.

There is an urgent need for novel agents to treat drug-resistant bacterial infections, such as multidrug-resistant Staphylococcus aureus (MRSA). Desirable properties for new antibiotics include high potency, narrow species selectivity, low propensity to elicit new resistance phenotypes, and synergy with standard of care (SOC) chemotherapies. Here, we describe analysis of the anti-MRSA potential exhibited by F12, an innovative anti-MRSA lysin that has been genetically engineered to evade detrimental antidrug immune responses in human patients. F12 possesses high potency and rapid onset of action, it has narrow selectivity against pathogenic Staphylococci, and it manifests synergy with numerous SOC antibiotics. Additionally, resistance to F12 and β-lactam antibiotics appears mutually exclusive, and importantly we provide evidence that F12 re-sensitizes normally resistant MRSA strains to β-lactams both in vitro and in vivo These results suggest that combinations of F12 and SOC antibiotics could be a promising new approach to treating refractory S. aureus infections.

There is an urgent need for novel agents to treat drug-resistant bacterial infections, such as multidrug-resistant Staphylococcus aureus (MRSA). Desirable properties for new antibiotics include high potency, narrow species selectivity, low propensity to elicit new resistance phenotypes, and synergy with standard-of-care (SOC) chemotherapies. Here, we describe analysis of the antibacterial potential exhibited by F12, an innovative anti-MRSA lysin that has been genetically engineered to evade detrimental antidrug immune responses in human patients. F12 possesses high potency and rapid onset of action, it has narrow selectivity against pathogenic staphylococci, and it manifests synergy with numerous SOC antibiotics. Additionally, resistance to F12 and β-lactam antibiotics appears mutually exclusive, and, importantly, we provide evidence that F12 resensitizes normally resistant MRSA strains to β-lactams both in vitro and in vivo. These results suggest that combinations of F12 and SOC antibiotics are a promising new approach to treating refractory S. aureus infections.

A deimmunized lysostaphin biotherapy evades detrimental antidrug immune reactions and has improved efficacy for MRSA infections., There is a critical need for novel therapies to treat methicillin-resistant Staphylococcus aureus (MRSA) and other drug-resistant pathogens, and lysins are among the vanguard of innovative antibiotics under development. Unfortunately, lysins’ own microbial origins can elicit detrimental antidrug antibodies (ADAs) that undermine efficacy and threaten patient safety. To create an enhanced anti-MRSA lysin, a novel variant of lysostaphin was engineered by T cell epitope deletion. This “deimmunized” lysostaphin dampened human T cell activation, mitigated ADA responses in human HLA transgenic mice, and enabled safe and efficacious repeated dosing during a 6-week longitudinal infection study. Furthermore, the deimmunized lysostaphin evaded established anti–wild-type immunity, thereby providing significant anti-MRSA protection for animals that were immune experienced to the wild-type enzyme. Last, the enzyme synergized with daptomycin to clear a stringent model of MRSA endocarditis. By mitigating T cell–driven antidrug immunity, deimmunized lysostaphin may enable safe, repeated dosing to treat refractory MRSA infections.

The accelerating spread of drug-resistant bacteria is creating demand for novel antibiotics. Bactericidal enzymes, such as human lysozyme (hLYZ), are interesting drug candidates due to their inherent catalytic nature and lack of susceptibility to the resistance mechanisms typically directed towards chemotherapeutics. However, natural antibacterial enzymes have their own limitations. For example, hLYZ is susceptible to pathogen derived inhibitory proteins, such as Escherichia coli Ivy. Here, we describe proof of concept studies demonstrating that hLYZ can be effectively redesigned to evade this potent lysozyme inhibitor. Large combinatorial libraries of hLYZ were analyzed using an innovative screening platform based on microbial co-culture in hydrogel microdroplets. Isolated hLYZ variants were orders of magnitude less susceptible to E. coli Ivy yet retained high catalytic proficiency and inherent antibacterial activity. Interestingly, the engineered escape variants showed a disadvantageous increase in susceptibility to the related Ivy ortholog from Pseudomonas aeruginosa as well as an unrelated E. coli inhibitory protein, MliC. Thus, while we have achieved our original objective with respect to escaping E. coli Ivy, engineering hLYZ for broad-spectrum evasion of proteinaceous inhibitors will require consideration of the complex and varied determinants that underlie molecular recognition by these emerging virulence factors.

Gel microdroplet – fluorescence activated cell sorting (GMD-FACS) is an innovative high throughput screening platform for recombinant protein libraries, and we show here that GMD-FACS can overcome many of the limitations associated with conventional screening methods for antibody libraries. For example, phage and cell surface display benefit from exceptionally high throughput, but generally require high quality, soluble antigen target and necessitate the use of anchored antibody fragments. In contrast, the GMD-FACS assay can screen for soluble, secreted, full-length IgGs at rates of several thousand clones per second, and the technique enables direct screening against membrane protein targets in their native cellular context. In proof-of-concept experiments, rare anti-EGFR antibody clones were efficiently enriched from a 10,000-fold excess of anti-CCR5 clones in just three days. Looking forward, GMD-FACS has the potential to contribute to antibody discovery and engineering for difficult targets, such as ion channels and G protein-coupled receptors.

The complete separation of structurally similar compounds has been a challenge due mainly to their similarity on physical and chemical properties. In the present study, a simple and effective chromatographic method to separate and purify nocathiacin acid from its structural analogue nocathiacin I was developed. After evaluating mobile phase compositions on the retention characteristics by reversed phase high-performance liquid chromatography (HPLC), the elution order of nocathiacin I and nocathiacin acid was completely reversed, and the resolution value between the two analogues was improved, by varying pH value and ionic strength, to greater than 10 from merged peaks under initial conditions. In addition, a preparative isolation of nocathiacin acid was performed by reversed phase column chromatography under the guidance of the HPLC study. This chromatographic method resulted in an efficient process to obtain pure nocathiacin acid with a recovery rate of 83%. The present approach offers a new methodology for the separation of structurally closely related secondary metabolites.

New Delhi metallo-β-lactmase-1 (NDM-1) has recently attracted extensive attention for its biological activities to catalyze the hydrolysis of almost all of β-lactam antibiotics. To study the catalytic property of NDM-1, the steady-kinetic parameters of NDM-1 toward several kinds of β-lactam antibiotics have been detected. It could effectively hydrolyze most β-lactams (k cat/K m ratios between 0.03 to 1.28 µmol⁻¹.s⁻¹), except aztreonam. We also found that thiophene-carboxylic acid derivatives could inhibit NDM-1 and have shown synergistic antibacterial activity in combination with meropenem. Flexible docking and quantum mechanics (QM) study revealed electrostatic interactions between the sulfur atom of thiophene-carboxylic acid derivatives and the zinc ion of NDM-1, along with hydrogen bond between inhibitor and His189 of NDM-1. The interaction models proposed here can be used in rational design of NDM-1 inhibitors.

Microbial generation of nocathiacin acid from nocathiacin I by manipulating enzymatic activities related to C-terminal dehydroalanine hydrolysis in Amycolatopsis fastidiosa LCB1001 was investigated by comparing the effects of various factors including metal ions, amino acid precursors and starting pH on the transformation. CuCl(2) and cysteine significantly increased bioconversion yields, and starting pH and time were also major factors affecting the product yield. Under optimal conditions, the yield of nocathiacin acid was increased from 10.4mg/L to greater than 45.0mg/L after 6days of fermentation. The use of protease inhibitors indicated that enzymes such as peptidylglycine monooxygenase and alcylase I are likely involved in the bioconversion. This is the first report on the generation of nocathiacin acid through microbial conversion in situ. Compared to chemical methods, the present approach is more effective and could be broadly applied in the production of novel derivatives of microbial secondary metabolites.