Characterization of gH/gL/pUL128-131 pentameric complex, gH/gL/gO trimeric complex, gB and gM/gN glycoproteins in a human cytomegalovirus using automated capillary western blots

An enveloped virus-like particle alum-adjuvanted cytomegalovirus vaccine is safe and immunogenic: A first-in-humans Canadian Immunization Research Network (CIRN) study

INTRODUCTION

Cytomegalovirus (CMV) is the most common cause of congenital infection and affected children often have permanent neurodevelopmental sequelae, including hearing loss and intellectual disability. Vaccines to prevent transmission of CMV during pregnancy are a public health priority. This first-in-humans dose-ranging, randomized, placebo-controlled, observer-blinded study evaluated the safety and immunogenicity of an enveloped virus-like particle (eVLP) vaccine expressing a modified form of the CMV glycoprotein B (gB).

METHODS

Healthy CMV-seronegative 18 to 40-year-olds at 3 Canadian study sites were randomized to one of 4 dose formulations (0.5 µg, 1 µg, or 2 µg gB content with alum) or 1 µg gB without alum, or placebo, given intramuscularly on days 0, 56 and 168. Outcome measures were solicited and unsolicited adverse events (AE), severe AE, gB and AD-2 epitope binding antibody titers and avidity, and neutralizing antibody (nAb) titers to CMV measured in fibroblast and epithelial cell infection assays.

RESULTS

Among 125 participants, the most common solicited local and general AEs were pain and headache, respectively. A dose-dependent increase in gB binding, avidity and nAb titers was observed after doses 2 and 3, with the highest titers in the alum-adjuvanted 2.0 µg dose recipients after the third dose; in the latter 24 % had responses to the broadly neutralizing AD-2 epitope. Neutralizing activity to CMV infection of fibroblasts was seen in 100 % of 2.0 µg alum-adjuvanted dose recipients, and to epithelial cell infection in 31 %. Epithelial cell nAb titers were positively correlated with higher geometric mean CMV gB binding titers.

CONCLUSIONS

An eVLP CMV vaccine was immunogenic in healthy CMV-seronegative adults and no safety signals were seen. Alum adjuvantation increased immunogenicity as did higher antigen content and a three dose schedule. This phase 1 trial supports further development of this eVLP CMV vaccine candidate.

Development and qualification of an automated capillary Western method for the identification of polysaccharide serotypes in pneumococcal conjugate vaccine (PCV)

Streptococcus pneumoniae bacterial infection causes mortality in both adults and infants. To mitigate the impact of the disease, several Pneumococcal conjugate vaccines (PCVs) have been manufactured for the U.S. market, including the recent approval of the 15-valent PCV Vaxneuvance™ from MSD. These vaccines demonstrate high efficacy for both the adult and pediatric dose. These PCVs contain multiple unique serotypes in the final, formulated vaccine product, and identifying a specific polysaccharide, in the presence of other serotypes, is a critical quality attribute that must be demonstrated through analytical testing. Here we describe the development and qualification of an identity assay using an automated capillary western system, called Simple Western, implementing a multi-valent system suitability sample (SSS) to determine individual polysaccharide components. The assay was optimized through rigorous analytical development and was successfully qualified for use in the clinical release of the PCV.

Safety, efficacy, and immunogenicity of a replication-defective human cytomegalovirus vaccine, V160, in cytomegalovirus-seronegative women: a double-blind, randomised, placebo-controlled, phase 2b trial

BACKGROUND

A vaccine that prevents cytomegalovirus (CMV) infection in women could reduce the incidence of congenital CMV infection, a major cause of neurodevelopmental disability. We aimed to assess the safety and efficacy of a replication-defective investigational CMV vaccine, V160, in CMV-seronegative women.

METHODS

This phase 2b, randomised, double-blind, placebo-controlled study was conducted at 90 sites in seven countries (USA, Finland, Canada, Israel, Spain, Russia, and Australia). Eligible participants were generally healthy, CMV-seronegative, non-pregnant, 16-35-year-old women of childbearing potential with exposure to children aged 5 years or younger. Participants were randomly assigned using central randomisation via an interactive response technology system 1:1:1 to one of three groups: V160 three-dose regimen (V160 at day 1, month 2, and month 6), V160 two-dose regimen (V160 on day 1, placebo at month 2, and V160 at month 6), or placebo (saline solution at day 1, month 2, and month 6). The primary outcomes were the efficacy of three doses of V160 in reducing the incidence of primary CMV infection during the follow-up period starting 30 days after the last dose of vaccine using a fixed event rate design, and the safety and tolerability of the two-dose and three-dose V160 regimens. We planned to test the efficacy of a two-dose regimen of V160 in reducing the incidence of primary CMV infection only if the primary efficacy hypothesis was met. Analyses for the primary efficacy endpoint were performed on the per-protocol efficacy population; safety analyses included all randomly assigned participants who received study vaccine. The primary efficacy hypothesis was tested at prespecified interim and final analyses. The study was ongoing and efficacy data continued to accrue at the time of final testing of the primary efficacy hypothesis. Vaccine efficacy was re-estimated after final testing of the primary efficacy hypothesis based on all available efficacy data at end of study. This trial is registered at ClinicalTrials.gov (NCT03486834) and EudraCT (2017-004233-86) and is complete.

FINDINGS

Between April 30, 2018, and Aug 30, 2019, 7458 participants were screened, of whom 2220 were randomly assigned to the V160 three-dose group (n=733), V160 two-dose group (n=733), or placebo group (n=734). A total of 523 participants in the V160 three-dose group and 519 in the placebo group were included in the final hypothesis testing. Of these, there were 11 cases of CMV infection in the V160 three-dose group and 20 cases in the placebo group. The vaccine efficacy for the V160 three-dose group was 44·6% (95% CI -15·2 to 74·8) at the final testing of the primary efficacy hypothesis, a result corresponding to failure to demonstrate the primary efficacy hypothesis. On the basis of this result, the study was terminated for futility. The re-estimate of vaccine efficacy for the V160 three-dose group based on all available efficacy data at end of study (556 participants in the V160 three-dose group and 543 in the placebo group) was 42·4% (95% CI -13·5 to 71·1). A total of 728 participants in the V160 three-dose group, 729 in the V160 two-dose group, and 732 in the placebo group were included in the safety analyses. The most common solicited injection-site adverse event was injection-site pain (680 [93%] in the V160 three-dose group, 659 [90%] in the V160 two-dose group, and 232 [32%] in the placebo group). The most common solicited systemic adverse event was fatigue (457 [63%] in the V160 three-dose group, 461 [63%] in the V160 two-dose group, and 357 [49%] in the placebo group). No vaccine-related serious adverse events or deaths were reported.

INTERPRETATION

V160 was generally well tolerated and immunogenic; however, three doses of the vaccine did not reduce the incidence of primary CMV infection in CMV-seronegative women compared with placebo. This study provides insights into the design of future CMV vaccine efficacy trials, particularly for the identification of CMV infection using molecular assays.

FUNDING

Merck Sharp & Dohme, a subsidiary of Merck & Co, Rahway, NJ, USA (MSD).

Recent applications of quantitative mass spectrometry in biopharmaceutical process development and manufacturing

Biopharmaceutical products have seen rapid growth over the past few decades and continue to dominate the global pharmaceutical market. Aligning with the quality by design (QbD) framework and realization, recent advances in liquid chromatography-mass spectrometry (LC-MS) instrumentation and related techniques have enhanced biopharmaceutical characterization capabilities and have supported an increased development of biopharmaceutical products. Beyond its routine qualitative characterization, the quantitative feature of LC-MS has unique applications in biopharmaceutical process development and manufacturing. This review describes the recent applications and implications of the advancement of quantitative MS methods in biopharmaceutical process development, and characterization of biopharmaceutical product, product-related variants, and process-related impurities. We also provide insights on the emerging applications of quantitative MS in the lifecycle of biopharmaceutical product development including quality control in the Good Manufacturing Practice (GMP) environment and process analytical technology (PAT) practices during process development and manufacturing. Through collaboration with instrument and software vendors and regulatory agencies, we envision broader adoption of phase-appropriate quantitative MS-based methods for the analysis of biopharmaceutical products, which in turn has the potential to enable manufacture of higher quality products for patients.

Investigation into the use of gamma irradiated Cytodex-1 microcarriers to produce a human cytomegalovirus (HCMV) vaccine candidate in epithelial cells

V160 is a viral vaccine candidate against human cytomegalovirus (HCMV) that is manufactured using Adult Retinal Pigment Epithelial cells (ARPE-19) grown on Cytodex-1 microcarriers. The microcarriers are generally hydrated, washed, and autoclaved prior to use, which can be limiting at large production scales. To minimize microcarrier preparation and sterilization, the use of gamma irradiated Cytodex-1 was investigated. Similar ARPE-19 cell growth was observed on heat-sterilized and gamma irradiated Cytodex-1; however, significantly reduced virus production was observed in cultures exposed to gamma irradiated Cytodex-1. Additional experiments suggest that infection inhibition is not exclusive to ARPE-19 but is most directly linked to HCMV V160, as evidenced by similar inhibition of V160 with Vero cells and no inhibition of Measles virus with either cell type. These observations suggest a putative impact on HCMV infection from the presence of extractable(s)/leachable(s) in the gamma irradiated microcarriers. Thorough aseptic rinsing of gamma irradiated Cytodex-1 prior to use can mitigate this impact and enable comparable process performance to heat-sterilized Cytodex-1. Though not fully a "ready-to-use" product for the HCMV V160 production process, utilization of Cytodex-1 microcarriers was possible without requiring heat sterilization, suggesting a potential path forward for large scale production of V160.

Understanding the Spike Protein in COVID-19 Vaccine in Recombinant Vesicular Stomatitis Virus (rVSV) Using Automated Capillary Western Blots

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the viral agent that is responsible for the coronavirus disease-2019 (COVID-19) pandemic. One of the live virus vaccine candidates Merck and Co., Inc. was developing to help combat the pandemic was V590. V590 was a live-attenuated, replication-competent, recombinant vesicular stomatitis virus (rVSV) in which the envelope VSV glycoprotein (G protein) gene was replaced with the gene for the SARS-CoV-2 spike protein (S protein), the protein responsible for viral binding and fusion to the cell membrane. To assist with product and process development, a quantitative Simple Western (SW) assay was successfully developed and phase-appropriately qualified to quantitate the concentration of S protein expressed in V590 samples. A strong correlation was established between potency and S-protein concentration, which suggested that the S-protein SW assay could be used as a proxy for virus productivity optimization with faster data turnaround time (3 h vs 3 days). In addition, unlike potency, the SW assay was able to provide a qualitative profile assessment of the forms of S protein (S protein, S1 subunit, and S multimer) to ensure appropriate levels of S protein were maintained throughout process and product development. Finally, V590 stressed stability studies suggested that time and temperature contributed to the instability of S protein demonstrated by cleavage into its subunits, S1 and S2, and aggregation into S multimer. Both of which could potentially have a deleterious effect on the vaccine immunogenicity.

Quantitation of Coxsackievirus A21 Viral Proteins in Mixtures of Empty and Full Capsids Using Capillary Western

A prototype strain of Coxsackievirus A21 (CVA21) is being evaluated as an oncolytic virus immunotherapy. CVA21 preferentially lyses cells that upregulate the expression of intercellular adhesion molecule 1, which includes some types of tumor cells. CVA21 has an icosahedral capsid structure made up of 60 protein subunits encapsidating a viral RNA genome with a particle diameter size of 30 nm. Rapid and robust analytical methods to quantify CVA21 total, empty, and full virus particles are important to support the process development, meet regulatory requirements, and validate manufacturing processes. In this study, we demonstrate the detection of all four CVA21 capsid proteins, VP1, VP2, VP3, and VP4, as well as VP0, a surrogate for empty particles, using in-house-generated antibodies. An automated and quantitative capillary Western blot assay, Simple Western, was developed using these antibodies to quantify CVA21 total particles through VP1, empty particles through VP0, relative ratio of empty to full particles through VP0 and VP4, and the absolute ratio of empty to total particles through VP0 and VP1. Finally, this Simple Western method was used to support CVA21 cell culture and purification process optimization as a high-throughput analytical tool to make rapid process decisions.