Safety and Effectiveness of Regdanvimab for COVID-19 Treatment: A Phase 4 Post-marketing Surveillance Study Conducted in South Korea.

INTRODUCTION: Regdanvimab, a neutralising monoclonal antibody (mAb) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), received approval for the treatment of coronavirus disease 2019 (COVID-19) in South Korea in 2021. The Ministry of Food and Drug Safety in South Korea mandate that new medications be re-examined for safety and effectiveness post-approval in at least 3000 individuals. This post-marketing surveillance (PMS) study was used to evaluate the safety and effectiveness of regdanvimab in real-world clinical care. METHODS: This prospective, multicentre, phase 4 PMS study was conducted between February 2021 and March 2022 in South Korea. Eligible patients were aged ≥ 18 years with confirmed mild COVID-19 at high risk of disease progression or moderate COVID-19. Patients were hospitalised and treated with regdanvimab (40 mg/kg, day 1) and then monitored until discharge, with a follow-up call on day 28. Adverse events (AEs) were documented, and the COVID-19 disease progression rate was used to measure effectiveness. RESULTS: Of the 3123 patients with COVID-19 infection identified, 3036 were eligible for inclusion. Approximately 80% and 5% of the eligible patients were diagnosed with COVID-19 during the delta- and omicron-dominant periods, respectively. Median (range) age was 57 (18-95) years, and 50.6% of patients were male. COVID-19 severity was assessed before treatment, and high-risk mild and moderate COVID-19 was diagnosed in 1030 (33.9%) and 2006 (66.1%) patients, respectively. AEs and adverse drug reactions (ADRs) were experienced by 684 (22.5%) and 363 (12.0%) patients, respectively. The most common ADR was increased liver function test (n = 62, 2.0%). Nine (0.3%) patients discontinued regdanvimab due to ADRs. Overall, 378 (12.5%) patients experienced disease progression after regdanvimab infusion, with extended hospitalisation/re-admission (n = 300, 9.9%) as the most common reason. Supplemental oxygen was required by 282 (9.3%) patients. Ten (0.3%) patients required intensive care monitoring and 3 (0.1%) died due to COVID-19. CONCLUSION: This large-scale PMS study demonstrated that regdanvimab was effective against COVID-19 progression and had an acceptable safety profile when used in real-world clinical practice.

Safety and effectiveness of intravenous CT-P13 in inflammatory arthritis: post-marketing surveillance study in Thailand.

Background: The infliximab biosimilar CT-P13 was approved in Thailand in 2015. Methods: This open-label, multicenter, post-marketing surveillance study evaluated the safety (events of special interest [ESIs]; primary end point) and effectiveness of 46 weeks of CT-P13 treatment according to routine practice in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), or psoriatic arthritis (PsA), with 1 year follow-up post-treatment. Results: 30 patients were enrolled (16 RA, 8 AS and 6 PsA). Infections were the most frequently reported study drug-related ESIs (2 RA and 2 AS). One patient with RA and one with PsA experienced infusion-related reactions. No cases of tuberculosis, malignancy (as expected, given 1 year follow-up), or drug-induced liver disease were reported. Disease activity improved across indications. Conclusion: CT-P13 was well tolerated and effective across indications.

Infliximab is one biological medicine used to treat inflammatory diseases, including rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA). CT-P13 is a near-identical copy, called a biosimilar, of the original ('reference') version of infliximab. CT-P13 is the first biosimilar to receive regulatory approval for treatment of the same three diseases from the European Medicines Agency (EMA) and US Food and Drug Administration. Biosimilarity means that CT-P13 does not differ from the original version of infliximab in clinically important ways, such as how safe it is and how well it works. CT-P13 and reference infliximab provided similar symptom relief during previous clinical trials, and both drugs caused similar side effects. It is important to monitor the safety and performance of CT-P13 when given during routine clinical practice, and in different ethnic populations, such as through the study reported here. Following regulatory approval in Thailand, 30 patients prescribed CT-P13 during routine clinical practice participated in this study. The study included 16 patients with RA, eight with AS and six with PsA. The patients took CT-P13 for 46 weeks and were monitored for a further year. Side effects of CT-P13 were as expected based on previous experience and did not raise any safety concerns. Based on the known safety profile of CT-P13, the study looked at some side effects in particular: infections were the most common of these side effects, experienced by 16 patients overall (seven patients with RA, five patients with AS and four patients with PsA). CT-P13 improved symptoms for all of the diseases. The study suggests that CT-P13 can be given safely and reduces symptoms in Thai patients with AS, RA or PsA. Thai Clinical Trials Registry: TCTR20170817005 (www.thaiclinicaltrials.org/show/TCTR20170817005).

Six-Year Survival Outcomes for Patients with HER2-Positive Early Breast Cancer Treated with CT-P6 or Reference Trastuzumab: Observational Follow-Up Study of a Phase 3 Randomised Controlled Trial.

BACKGROUND: The Phase 3 CT-P6 3.2 study demonstrated equivalent efficacy and comparable safety between CT-P6 and reference trastuzumab in patients with human epidermal growth factor receptor-2 (HER2)-positive early breast cancer after up to 3 years' follow-up. OBJECTIVE: To investigate long-term survival with CT-P6 and reference trastuzumab. METHODS: In the CT-P6 3.2 study, patients with HER2-positive early breast cancer were randomised to neoadjuvant chemotherapy with CT-P6 or reference trastuzumab, surgery, and adjuvant CT-P6 or reference trastuzumab before a 3-year post-treatment follow-up. Patients who completed the study could enter a 3-year extension (CT-P6 4.2 study). Data were collected every 6 months to assess overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS). RESULTS: Of 549 patients enrolled in the CT-P6 3.2 study, 216 (39.3%) patients continued in the CT-P6 4.2 study (CT-P6, 107; reference trastuzumab, 109) (intention-to-treat extension set). Median follow-up was 76.4 months for both groups. Medians were not reached for time-to-event parameters; estimated hazard ratios (95% confidence intervals) for CT-P6 versus reference trastuzumab were 0.59 (0.17-2.02) for OS, 1.07 (0.50-2.32) for DFS, and 1.08 (0.50-2.34) for PFS. Corresponding 6-year survival rates in the CT-P6 and reference trastuzumab groups, respectively, were 0.96 (0.90-0.99) and 0.94 (0.87-0.97), 0.87 (0.78-0.92) and 0.89 (0.81-0.94), and 0.87 (0.78-0.92) and 0.89 (0.82-0.94). CONCLUSIONS: Data from this extended follow-up of the CT-P6 3.2 study demonstrate the comparable long-term efficacy of CT-P6 and reference trastuzumab up to 6 years. EUDRACT NUMBER: 2019-003518-15 (retrospectively registered 10 March 2020).

A non-interventional, post-marketing surveillance study evaluating the safety and effectiveness of biosimilar rituximab (CT-P10) during routine clinical practice in the Republic of Korea.

BACKGROUND: CT-P10 was the first licensed rituximab biosimilar. This Korean post-marketing surveillance study evaluated CT-P10 safety and effectiveness in approved indications. RESEARCH DESIGN AND METHODS: This prospective, open-label, observational, phase 4 study collected routine clinical practice data across 27 centers in the Republic of Korea. Patients received their first CT-P10 treatment, per prescribing information, for non-Hodgkin's lymphoma (NHL), chronic lymphocytic leukemia (CLL), rheumatoid arthritis (RA), granulomatosis with polyangiitis (GPA), or microscopic polyangiitis (MPA) during the surveillance period (16 November 2016-15 November 2020). Safety (including adverse events [AEs] and adverse drug reactions [ADRs]) and disease-specific clinical response (by best overall response [NHL/CLL], Disease Activity Score in 28-joints [RA], or Birmingham Vasculitis Activity Score for Wegener's Granulomatosis [GPA/MPA]) were assessed for ≤1 year (NHL/CLL) or ≤24 weeks (RA/GPA/MPA). RESULTS: The safety population comprised 677 patients (604 NHL, 16 CLL, 42 RA, 7 GPA, 8 MPA). AEs/ADRs were reported for 68.4%/27.7% (NHL/CLL), 31.0%/14.3% (RA), and 86.7%/13.3% (GPA/MPA) of patients. Serious AEs and unexpected ADRs did not raise new safety signals. Pneumonia was the most frequent serious ADR overall. Positive effectiveness outcomes were observed. CONCLUSIONS: Findings were consistent with the known CT-P10/reference rituximab safety profile, with high effectiveness observed in NHL/CLL and RA.

Pharmacokinetic equivalence of CT-P39 and reference omalizumab in healthy individuals: A randomised, double-blind, parallel-group, Phase 1 trial.

BACKGROUND: CT-P39 is being developed as a biosimilar of reference omalizumab. This study aimed to assess the pharmacokinetic equivalence of CT-P39 to European Union-approved and United States-licensed reference omalizumab (EU- and US-omalizumab, respectively). METHODS: This two-part, randomised, parallel-group, double-blind Phase 1 trial (NCT04018313) was conducted in healthy individuals with a total immunoglobulin E (IgE) level ≤100  international units (IU)/ml at screening. In part 2, described herein, participants were randomised (1:1:1) to receive a single 150 mg subcutaneous dose of CT-P39, EU-omalizumab, or US-omalizumab. The primary endpoint was pharmacokinetic equivalence in terms of area under the concentration-time curve (AUC) from time zero to the last quantifiable concentration (AUC0-last ), AUC from time zero to infinity (AUC0-inf ), and maximum serum concentration (Cmax ). Equivalence was concluded if 90% confidence intervals (CIs) of the geometric least-squares means ratios were contained within the predefined 80%-125% equivalence margin. Additional pharmacokinetic parameters, pharmacodynamics, safety, and immunogenicity were also evaluated. RESULTS: Overall, 146 participants were randomised (CT-P39, N = 47; EU-omalizumab, N = 49; US-omalizumab, N = 50). For all primary pharmacokinetic parameters, 90% CIs for pairwise treatment comparisons were within the 80%-125% equivalence margin, demonstrating pharmacokinetic equivalence. Decreases in free IgE and increases in total IgE serum concentrations were comparable across groups. CT-P39 was well tolerated. Safety endpoints were comparable across groups: there were no treatment-related serious adverse events, deaths, or discontinuations due to treatment-emergent adverse events. CONCLUSIONS: CT-P39 was well tolerated and demonstrated pharmacokinetic equivalence with EU-omalizumab and US-omalizumab following administration of a single dose in healthy individuals.

Candidate Bevacizumab Biosimilar CT-P16 versus European Union Reference Bevacizumab in Patients with Metastatic or Recurrent Non-Small Cell Lung Cancer: A Randomized Controlled Trial.

BACKGROUND: CT-P16 is a candidate bevacizumab biosimilar. OBJECTIVE: This double-blind, multicenter, parallel-group, phase III study aimed to establish equivalent efficacy between CT-P16 and European Union-approved reference bevacizumab (EU-bevacizumab) in patients with metastatic or recurrent non-squamous non-small cell lung cancer (nsNSCLC). PATIENTS AND METHODS: Patients with stage IV or recurrent nsNSCLC were randomized (1:1) to receive CT-P16 or EU-bevacizumab (15 mg/kg every 3 weeks; ≤ 6 cycles) with paclitaxel (200 mg/m2) and carboplatin (area under the curve 6.0; both for 4-6 cycles), as induction therapy. Patients with controlled disease after induction therapy continued with CT-P16 or EU-bevacizumab maintenance therapy. The primary endpoint was objective response rate (ORR) during the induction period. Time-to-event analyses, pharmacokinetics, safety, and immunogenicity were also evaluated. Results obtained after 1 year of follow-up are presented. RESULTS: Overall, 689 patients were randomized (CT-P16, N = 342; EU-bevacizumab, N = 347). ORR was 42.40% (95% confidence interval [CI] 37.16-47.64) and 42.07% (95% CI 36.88-47.27) for CT-P16 and EU-bevacizumab, respectively. The risk difference (0.40 [95% CI - 7.02 to 7.83]) and risk ratio (1.0136 [90% CI 0.8767-1.1719]) for ORR fell within predefined equivalence margins (- 12.5 to + 12.5%, and 0.7368 to 1.3572, respectively), demonstrating equivalence between CT-P16 and EU-bevacizumab. Median response duration, time to progression, progression-free survival, and overall survival were comparable between treatment groups. Safety profiles were similar: 96.2% (CT-P16) and 93.0% (EU-bevacizumab) of patients experienced treatment-emergent adverse events. Pharmacokinetics and immunogenicity were comparable between groups. CONCLUSIONS: Equivalent efficacy and similar pharmacokinetics, safety, and immunogenicity support bioequivalence of CT-P16 and EU-bevacizumab in patients with nsNSCLC. TRIAL REGISTRATION NUMBER: NCT03676192.

Preclinical assessment and randomized Phase I study of CT-P63, a broadly neutralizing antibody targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in significant morbidity and mortality worldwide. Despite a successful vaccination programme, the emergence of mutated variants that can escape current levels of immunity mean infections continue. Herein, we report the development of CT-P63, a broad-spectrum neutralizing monoclonal antibody. In vitro studies demonstrated potent neutralizing activity against the most prevalent variants, including Delta and the BA.1 and BA.2 sub-lineages of Omicron. In a transgenic mouse model, prophylactic CT-P63 significantly reduced wild-type viral titres in the respiratory tract and CT-P63 treatment proved efficacious against infection with Beta, Delta, and Omicron variants of SARS-CoV-2 with no detectable infectious virus in the lungs of treated animals. A randomized, double-blind, parallel-group, placebo-controlled, Phase I, single ascending dose study in healthy volunteers (NCT05017168) confirmed the safety, tolerability, and pharmacokinetics of CT-P63. Twenty-four participants were randomized and received the planned dose of CT-P63 or placebo. The safety and tolerability of CT-P63 were evaluated as primary objectives. Eight participants (33.3%) experienced a treatment-emergent adverse event (TEAE), including one grade ≥3 (blood creatine phosphokinase increased). There were no deaths, treatment-emergent serious adverse events, TEAEs of special interest, or TEAEs leading to study drug discontinuation in the CT-P63 groups. Serum CT-P63 concentrations rapidly peaked before declining in a biphasic manner and systemic exposure was dose proportional. Overall, CT-P63 was clinically safe and showed broad-spectrum neutralizing activity against SARS-CoV-2 variants in vitro and in vivo.

Long-term efficacy and safety of CT-P10 or rituximab in untreated advanced follicular lymphoma: a randomized phase 3 study.

Rituximab biosimilars are a cornerstone of treatment of advanced-stage follicular lymphoma (FL). This double-blind, parallel-group, phase 3 trial randomized (1:1) adults (≥18 years) with stage III to IV indolent B-cell lymphoma, including grades 1 to 3a FL, to receive CT-P10 or rituximab (375 mg/m2 IV), with cyclophosphamide, vincristine, and prednisone, every 3 weeks for 8 cycles (induction period). Patients achieving complete response (CR), unconfirmed CR, or partial response (PR) received CT-P10 or rituximab maintenance for 2 years (375 mg/m2, every 8 weeks). Primary end points were previously reported, proving noninferiority of efficacy and pharmacokinetic equivalence of CT-P10 to rituximab. Secondary end points included overall response rate (PR+CR) during the induction period per 2007 International Working Group (IWG) criteria, survival analyses, and overall safety. Between 28 July 2014 and 29 December 2015, 140 patients were randomized (70 per group). Median follow-up was 39.9 months (interquartile range, 36.7-43.5). Per 1999 IWG criteria, 4-year Kaplan-Meier estimates (95% confidence interval [CI]) for CT-P10 and rituximab were 61% (47% to 73%) and 55% (36% to 70%) for progression-free survival (hazard ratio, 1.33 [95% CI, 0.67-2.63]; P=.409), respectively, and 88% (77% to 94%) and 93% (83% to 97%) for overall survival (5.29 [0.84-33.53]; P=.077). Overall, 90% (CT-P10) and 86% (rituximab) of patients experienced treatment-emergent adverse events. Long-term safety profiles were similar between groups. Findings confirm favorable outcomes for CT-P10-treated patients with advanced-stage FL and demonstrate comparable long-term efficacy and overall safety between CT-P10 and rituximab. This trial was registered at www.clinicaltrials.gov as #NCT02162771.

Adjuvant effect of B domain of staphyloccocal protein A displayed on the surface of hepatitis B virus capsid.

The hepatitis B virus (HBV) capsid-based recombinant particles, which display both major hydrophilic region of HBV surface antigen (HBV-MHR) and B domain of Staphylococcal protein A (SPAB ), were produced using Escherichia coli as expression host. SPAB was used as an adjuvant to elicit the immune response to HBV-MHR, and its adjuvant effect in the immunized mice was estimated with varying the position and amount of SPAB on the HBV capsid particles. Compared to the emulsified aluminum gel (alum gel) that is a currently commercialized vaccine adjuvant, SPAB caused the significantly higher level of anti-HBV immunoglobulin G (IgG) titer and seroconversion rate, and notably SPAB at the most surface-exposed position on the recombinant particle led to the highest immune response. Moreover, SPAB caused much lower ratio of IgG1 to IgG2a compared to alum gel, indicating that helper T-cell 1-mediated immune response (responsible for cytotoxic T-cell stimulation) is relatively more stimulated by SPAB , unlike alum gel that mainly stimulates helper T-cell 2-mediated immune response (responsible for B-cell stimulation). Although HBV-MHR and HBV capsid particle were used as proof-of-concept in this study, SPAB can be used as a highly effective adjuvant with other disease-specific antigens on the surface of other virus-like particles to produce various recombinant vaccines with high potency.

Self-assembled proteinticle nanostructures for 3-dimensional display of antibodies.

"Proteinticle" is a nano-scale protein particle that is self-assembled inside cells with constant 3D structure and surface topology. The binding of IgG to the B domain of Staphylococcal protein A (SPA(B)) molecules that are genetically inserted on the surface of proteinticle enables the variable domains of bound IgG to be well oriented to effectively capture antigens, accordingly forming a highly sensitive 3D IgG probe. The five different proteinticles that originate from humans, bacteria, and virus and totally differ in size, shape, and surface structure were used for the surface display of SPA(B). The dissociation constant (K(D)) in the binding of IgG to SPA(B) on the proteinticle surface was estimated based on the Langmuir adsorption isotherm model: K(D) was 1-3 orders-of-magnitude lower compared to the previously reported K(D) in the binding of IgG to Staphylococcal protein A. The surface density and distribution of SPA(B) and especially the existence of hot (or highly congested) spots of SPA(B), which depend on the surface structure and the number of subunits as well as size and shape of proteinticle, is of crucial importance for the effective binding of IgG to SPA(B) on proteinticles. Although the five different proteinticles were demonstrated as proof-of-concept here, SPA(B)-mediated immobilization of IgG on the other proteinticles would be very useful for the fabrication of sensitive 3D immunoassay platforms.

Synthesis of Mycoplasma arginine deiminase in E. coli using stress-responsive proteins.

We found Escherichia coli proteins, elongation factor Ts (Tsf), and malate dehydrogenase (Mdh) that can exist in the form of native and soluble proteins even under stress situation such as heat shock and protein denaturing condition. To examine their property as solubility enhancers, aggregation-prone Mycoplasma arginine deiminase (mADI), which has been suggested as anti-cancer agent, was fused to the C-terminal of each of them and cloned into pET28a to be expressed in the E. coli cytoplasm. When mADI was fused to fusion partners (Mdh, Tsf), a significant portion of the recombinant mADI was expressed in a soluble fraction (>90%) whereas the directly expressed mADI was aggregated to the inclusion body. In addition, recombinant mADI released from the fusion tag retained its soluble form and presented its specific enzymatic activity of converting l-arginine into citrulline (>10 U/mg). These results show that Tsf and Mdh could serve as effective solubility enhancers for aggregation-prone proteins (e.g. mADI in this case) when used as fusion expression partners in bacterial expression systems.

Engineered protein nanoparticles for in vivo tumor detection.

Two different protein nanoparticles that are totally different in shape and surface structure, i.e. Escherichia coli DNA-binding protein (eDPS) (spherical, 10 nm) and Thermoplasma acidophilum proteasome (tPTS) (cylindrical, 12 × 15 nm) were engineered for in vivo optical tumor detection: arginine-glycine-aspartic acid (RGD) peptide (CDCRGDCFC) was genetically inserted to the surface of each protein nanoparticle, and also near-infrared fluorescence dye was chemically linked to the surface lysine residues. The specific affinity of RGD for integrin (αvß3) facilitated the uptake of RGD-presenting protein nanoparticles by integrin-expressing tumor cells, and also the protein nanoparticles neither adversely affected cell viability nor induced cell damage. After intravenously injected to tumor-bearing mice, all the protein nanoparticles successfully reached tumor with negligible renal clearance, and then the surface RGD peptides caused more prolonged retention of protein nanoparticles in tumor and accordingly higher fluorescence intensity of tumor image. In particular, the fluorescence of tumor image was more intensive with tPTS than eDPS, which is due presumably to longer in vivo half-life and circulation of tPTS that originates from thermophilic and acidophilic bacterium. Although eDPS and tPTS were used as proof-of-concept in this study, it seems that other protein nanoparticles with different size, shape, and surface structure can be applied to effective in vivo tumor detection.

A simple one-step assay platform based on fluorescence quenching of macroporous silicon.

We synthesized 3D macroporous silicon through a simple electrochemical dissolution process and systematically estimated its protein adsorption and effect on fluorescence emission. Compared with conventional 2D polystyrene plate, the macroporous silicon showed a superior protein adsorption capacity and significant fluorescence quenching effect. We developed a 3D macroporous silicon-based adenosine assay system through the following fabrication process: streptavidin molecules that have been immobilized on the surface of macroporous silicon are attached with biotin-linked and adenosine-specific DNA aptamer, followed by hybridization between the attached aptamer and fluorescent chemical (carboxytetramethylrhodamine/CTMR) that is conjugated with a short complementary DNA sequence. In the absence of adenosine, the aptamer-CTMR complexes remain closely attached to the surface of porous silicon, hence fluorescence being significantly quenched. Upon binding to adenosine, the DNA aptamer is subject to structure switching that leads to dissociation of CTMR from DNA aptamer, and consequently the CTMR fluorescence is restored, indicating a simple one-step assay of adenosine. Compared to the conventional 2D PS and ZnO nanorods-based assays, adenosine at much lower (sub-micromolar) concentration was successfully detected through the 3D macroporous silicon-based assay. The three-dimensionally and densely immobilized aptamer probes and effective fluorescence quenching on the surface of macroporous silicon enables adenosine to be detected at lower levels. Although the adenosine detection is reported here as a proof-of-concept, the developed macroporous silicon-based simple one-step assay platform can be applied in general to fluorescence quenching -based detection of many other biomolecules.

YrhB is a highly stable small protein with unique chaperone-like activity in Escherichia coli BL21(DE3).

Escherichia coli YrhB (10.6 kDa) from strain BL21(DE3) that is commonly used for protein overexpression is a stable chaperone-like protein and indispensable for supporting the growth of BL21(DE3) at 48 °C but not defined as conventional heat shock protein (HSP). YrhB effectively prevented heat-induced aggregation of ribonucleotide synthetase (PurK). Without ATP, YrhB alone promoted in vitro refolding of uridine phosphorylase (UDP) and protected thermal denaturation of the refolded UDP. As a cis-acting fusion partner, YrhB also significantly reduced inclusion body formation of nine aggregation-prone heterologous proteins in BL21(DE3). Unlike conventional small HSPs, YrhB remained monomer under heat shock condition.

A sensitive diagnostic assay of rheumatoid arthritis using three-dimensional ZnO nanorod structure.

We synthesized a three-dimensional nanorod structure of zinc oxide (ZnO) using a simple sol-gel process and systematically investigated properties of the ZnO nanorods regarding protein adsorption and effect on fluorescence emission. As compared to conventional polystyrene plate that has been widely used for strong protein adsorption, the ZnO nanorods had a superior protein adsorption capacity and significantly amplified fluorescence emission, suggesting the ZnO nanorods are attractive for fluorescence-based biomolecular detection assays. When applied to diagnostic assay of rheumatoid arthritis (RA) using cyclic citrullinated peptide (CCP) probe with a RCGRS motif that reportedly has a strong affinity for ZnO, the ZnO nanorods gave apparently high positive signals for all the RA-positive standards and patient sera, whereas upon the detection using conventional polystyrene plate, all the detection signals were relatively negligible. Moreover, the streptavidin-mediated immobilization of well oriented CCP further enhanced sensitivity, even for a 5000-times diluted patient serum. A highly sensitive detection of a very small amount of RA autoantibodies is important because individuals at high risk of developing RA can be identified several years before the clinical onset. Consequently, the fluorescence-based sensitive assay of RA was successfully performed using the three-dimensional ZnO nanorods, owing to the fluorescence amplification and protein/peptide adsorption properties and dimensionality of ZnO nanorods that in turn increases probe accessibility to anti-CCP RA autoantibodies. Although RA was assayed here for proof-of-concept, the ZnO nanorods-based assay can be applied in general to sensitive detection of a wide variety of antibody or protein targets.

Fluorescent ferritin nanoparticles and application to the aptamer sensor.

We synthesized fluorescent ferritin nanoparticles (FFNPs) through bacterial expression of the hybrid gene consisting of human ferritin heavy chain (hFTN-H), spacer (glycine-rich peptide), and enhanced green (or red) fluorescent protein [eGFP (or DsRed)] genes. The self-assembly activity of hFTN-H that leads to the formation of nanoparticles (12 nm in diameter), the conformational flexibility of the C-terminus of hFTN-H, and the glycine-rich spacer enabled eGFPs (or DsReds) to be well displayed on the surface of each ferritin nanoparticle, resulting in the construction of green (or red) FFNPs [gFFNPs (or rFFNPs)]. As compared to eGFP (or DsRed) alone, it is notable that the developed FFNPs showed significantly amplified fluorescence intensity and also enhanced stability. DNA aptamers were chemically conjugated to gFFNP via each eGFP's cysteine residue that was newly introduced through site-directed mutagenesis (Ser175Cys). The DNA-aptamer-conjugated gFFNPs were used as a fluorescent reporter probe in the aptamer-based "sandwich" assay of a cancer marker [i.e., platelet-derived growth factor B-chain homodimer (PDGF-BB)] in phosphate-buffered saline buffer or diluted human serum. This is a simple two-step assay without any additional steps for signal amplification, showing that compared to the same aptamer-based assays using eGFP alone or Cy3, the detection signals, affinity of the reporter probe to the cancer marker, and assay sensitivity were significantly enhanced; i.e., the limit of detection was lowered to the 100 fM level. Although the PDGF-BB assay is reported here as a proof-of-concept, the developed FFNPs can be applied in general to any aptamer-based sandwich assays.

Lyophilization and enhanced stability of fluorescent protein nanoparticles.

Protein nanoparticles (PNPs) that are nanostructured biomaterials with intrinsic biological function have been widely employed as three-dimensional nanobiomaterials for sensitive bioassays, MRI contrast, semiconductor devices, template for hybrid materials, etc., and stable and long-term maintenance of PNPs seems to be of crucial importance. We evaluated the stability of PNPs and the efficacy of lyophilization for the long-term stability of PNPs, especially using green fluorescent protein nanoparticles (gFPNPs) as a model PNP. Fluorescence intensities and TEM images of gFPNPs were analyzed to monitor their functional and structural stabilities. Unlike the green fluorescent protein monomers (eGFP) that were gradually inactivated in aqueous solution, gFPNP in the same aqueous solution retained the initial fluorescence activity and spherical nanoparticle structure even for 2 weeks at 4°C. To ensure stable and long-term maintenance of gFPNPs, gFPNPs in aqueous solution were converted to the dried solid forms through lyophilization. It is notable that fluorescence activity and nanoparticle structure of gFPNPs that were lyophilized with both Tween 80 and sucrose were very stably maintained even for 10weeks at various storage temperatures (-20°C, 4°C, 25°C, and 37°C). During the period of 10weeks, the fluorescence of gFPNP was always more than 80% level of initial fluorescence at a wide range of temperature. Although this stability study was focused on gFPNPs, the developed optimal lyophilization conditions for gFPNPs can be applied in general to stable and long-term maintenance of many other PNP-derived biomaterials.

Human G-CSF synthesis using stress-responsive bacterial proteins.

We previously reported that under the stress condition caused by the addition of 2-hydroxyethyl disulfide, a thiol-specific oxidant, to growing cultures of Escherichia coli BL21(DE3), a population of stress-responsive proteins [peptidyl-prolyl cis-trans isomerase B (PpiB), bacterioferritin (Bfr), putative HTH-type transcriptional regulator yjdC (YjdC), dihydrofolate reductase (FolA), chemotaxis protein cheZ (CheZ), and glutathione synthetase (GshB)] were significantly upregulated when compared with the nonstress condition. When those stress-responsive proteins were used as fusion partners for the expression of human granulocyte colony-stimulating factor (hG-CSF), the solubility of hG-CSF was dramatically enhanced in E. coli cytoplasm, whereas almost all of the directly expressed hG-CSF were aggregated to inclusion bodies. In addition, the spectra of circular dichroism measured with the purified hG-CSF were identical to that of standard hG-CSF, implying that the synthesized hG-CSF has native conformation. These results indicate that the bacterial stress-responsive proteins could be potent fusion expression partners for aggregation-prone heterologous proteins in E. coli cytoplasm.

A highly sensitive and selective diagnostic assay based on virus nanoparticles.

Early detection of the protein marker troponin I in patients with a higher risk of acute myocardial infarction can reduce the risk of death from heart attacks. Most troponin assays are currently based on the conventional enzyme linked immunosorbent assay and have detection limits in the nano- and picomolar range. Here, we show that by combining viral nanoparticles, which are engineered to have dual affinity for troponin antibodies and nickel, with three-dimensional nanostructures including nickel nanohairs, we can detect troponin levels in human serum samples that are six to seven orders of magnitude lower than those detectable using conventional enzyme linked immunosorbent assays. The viral nanoparticle helps to orient the antibodies for maximum capture of the troponin markers. High densities of antibodies on the surfaces of the nanoparticles and nanohairs lead to greater binding of the troponin markers, which significantly enhances detection sensitivities. The nickel nanohairs are re-useable and can reproducibly differentiate healthy serum from unhealthy ones. We expect other viral nanoparticles to form similar highly sensitive diagnostic assays for a variety of other protein markers.