Assays

Balancing the Statistical Tightrope

During one development meeting early in my industrial career, a process development group member asked me whether the value my group had reported in one result was okay to use. I confidently replied “Yes, it’s fine. It’s about 40, somewhere between 38 and 42. The other person raised his eyebrows. “About 40?” In response, I somewhat awkwardly mumbled “Yes, probably…about that” — an answer not met with full understanding, but rather concern. My answer hadn’t been incorrect. The result was…

Development of an In-House, Process-Specific ELISA for Detecting HCP in a Therapeutic Antibody, Part 2

    During biopharmaceutical manufacturing, final drug products can get contaminated with host-cell proteins (HCPs) derived from a production cell line. HCPs can elicit adverse immune responses, so regulatory authorities require accurate monitoring of their presence and concentration in final drug products. Because they are robust and offer good throughput, enzyme-linked immunosorbent assays (ELISAs) are the first choice for HCP detection to monitor product quality. Generic ELISA kits are commercially available for HCP detection with a number of commonly used…

Development of an In-House, Process-Specific ELISA for Detecting HCP in a Therapeutic Antibody, Part 1

    After production and purification of biopharmaceuticals generated by cell culture expression systems, endogenous cell line proteins — commonly referred to as host-cell proteins (HCPs) — sometimes contaminate finished products. HCPs can elicit an immune response following administration of those drugs to patients (1), and cause potentially deleterious side effects. It is therefore imperative to minimize HCP contamination in finished biologics. Regulatory health authorities require monitoring of HCP contamination. They expect validation of each purification process to demonstrate its…

A Biomass Monitor for Disposable Bioreactors

    Of the available on-line biomass assay types, radio-frequency impedance spectroscopy (RFI, often referred to as capacitance) is generally regarded as the most robust and reliable method for monitoring viable biomass during fermentation and cell culture. The first article to show that capacitance could be used to estimate microbial biomass dates back over 20 years (1). Today the technology is routinely used for monitoring and controlling mammalian cell culture processes and high-density yeast and bacterial fermentations in research, process…

Measuring Manufacturing Cost and Its Impact on Organizations

    The first article in this periodic series reviewed the impact of cost pressures on the biopharmaceutical industry, in particular the challenges the industry faces in relation to high capital costs, complex processes, and long product development cycles (1). Here we examine what companies are doing to assess costs in decisions about process and technology choices relating to manufacturing of biologic drug substances. We will look into what companies are currently doing and what they need to be doing…

Are Generic HCP Assays Outdated?

    Biomanufacturers face a conflict between low-cost generic host cell protein (HCP) assays and highly sensitive but more costly process-specific HCP assays that are usually not initiated until the proof-of-concept stage. But drug developers cannot expect sufficient sensitivity from most commercially available generic assays. For some companies, multiproduct HCP assays could offer a solution to the dilemma. Biopharmaceutical manufacture using genetically modified microorganisms and cell lines is typically associated with contamination by process-related impurities. One of the most important…

Improved HCP Quantitation By Minimizing Antibody Cross-Reactivity to Target Proteins

    Host cell proteins (HCPs) are process-related impurities derived from a host cell expression system that may be present in trace amounts in a final drug substance. During biologics development, it is important to demonstrate that a bioprocess is efficient in removing HCPs and that it provides consistent control of HCP levels. Several techniques are typically used for detection, quantitation, and risk evaluation of HCPs in biologics. The most common are enzyme-linked immunosorbent assays (ELISAs), Western blotting, sodium-dodecyl-sulfate polyacrylamide…

Accelerating Bioassay Transfer in a GMP Environment

Most products in discovery by pharmaceutical companies today are biopharmaceuticals. Made by living organisms, these are typically large–molecular-weight products that rely on their secondary and tertiary structure for therapeutic effectiveness. Synthetic small molecules and biopharmaceuticals both require analytical verification for release, but only biopharmaceuticals require functional potency assays for investigational new drug (IND), biological license application (BLA), and new drug application (NDA) submissions. Those activities often require elaborate transfers of diverse, biological, product specific assays that carry greater chances of…

Using In Vitro Assays for Therapeutic Enzyme Characterization

A number of biopharmaceuticals are enzymes that act in vivo on high-molecular substrates. It can be a challenge to develop in vitro methods for accurately assessing their biological activity. Interest is also developing in using enzyme kinetic parameters as product quality attributes under the quality-by-design (QbD) initiative. Among biotechnology therapeutics, the conventional method of expressing potency is in units/mg of biopolymer. For enzymes, a unit of activity was defined in 1958 by the International Union of Biochemistry and Molecular Biology…

Development and Qualification of a Generic IgG Quantification Assay Using Surface Plasmon Resonance

Fast, precise, and accurate quantification technologies are indispensable for efficient process development in applications such as IgG production in a GXP environment. Based on surface plasmon resonance (SPR) technology, the Biacore C system from GE Healthcare (www.biacore.com) is an alternative technology for IgG quantification that has benefits over traditional methods. Assay development is simplified and accelerated due to real-time detection. Assay hands-on time is reduced, and sample throughput can be increased using automation and efficient data evaluation with regulatory-compliant software.…