An In Vitro Assessment of Immunostimulatory Responses to Ten Model Innate Immune Response Modulating Impurities (IIRMIs) and Peptide Drug Product, Teriparatide

Using PBMCs in a Multiplex FluoroSpot Assay for Detection of Innate Immune Response-Modulating Impurities (IIRMIs)

The ELISA-based monocyte activation test (MAT) facilitates the replacement of the rabbit pyrogen test (RPT) for the detection of Innate Immune Response-Modulating Impurities (IIRMIs) in injectable drugs by activation of monocytes in human peripheral blood mononuclear cells (PBMCs). We describe the use of a triple-color IL-1β/IL-6/TNF-α FluoroSpot assay as a sensitive tool for quantification of the frequencies of IIRMI-activated monocytes as well as determination of the relative amount of pyrogenic cytokine(s) produced by each activated cell.

Immunogenicity risk assessment of synthetic peptide drugs and their impurities

Peptide drugs play an important part in medicine owing to their many therapeutic applications. Of the 80 peptide drugs approved for use in humans, at least five are now off-patent and are consequently being developed as generic alternatives to the originator products. To accelerate access to generic products, the FDA has proposed new regulatory pathways that do not require direct comparisons of generics to originators in clinical trials. The 'Abbreviated New Drug Application' (ANDA) pathway recommends that sponsors provide information on any new impurities in the generic drug, compared with the originator product, because the impurities can have potential to elicit unwanted immune responses owing to the introduction of T-cell epitopes. This review describes how peptide drug impurities can elicit unexpected immunogenicity and describes a framework for performing immunogenicity risk assessment of all types of bioactive peptide products. Although this report primarily focuses on generic peptides and their impurities, the approach might also be of interest for developers of novel peptide drugs who are preparing their products for an initial regulatory review.

Special Issue "Nanotechnology to Overcome the World's Most Critical Health Issues: Liposomes and Beyond-A Themed Issue Dedicated to Professor Yechezkel Barenholz"

This Special Issue is intended to celebrate Professor Yechezkel Barenholz's distinguished achievements [...].

Assessment of innate immune response modulating impurities in glucagon for injection

Glucagon for Injection is a polypeptide hormone medication used to treat patients with severe hypoglycemia or low blood sugar. Only recently, was a generic version of glucagon for injection approved by the FDA. While the generic version was deemed equivalent to its brand-name counterpart, the two glucagon products were produced using different manufacturing processes. The brand-name glucagon is produced via recombinant DNA while the generic glucagon is produced by peptide synthesis. Different manufacturing processes can result in different levels of innate immune response modulating impurities (IIRMIs). This study utilized a cell-based assay method, which allows for detection of a broad spectrum of impurities, to investigate the IIRMI risks of the generic glucagon to make sure it has similar or less immunogenicity risks than the brand-name glucagon product. Three commercial cell lines (RAW-Blue™, HEK-Blue™-hNOD1 and HEK-Blue™-hNOD2) carrying a secreted embryonic alkaline phosphatase reporter construct were used to quantify the level of innate immune responses after being treated with the glucagon drugs. The study results showed that despite differences in manufacturing process, the innate immunogenicity risk in the synthetic (generic) glucagon was at negligible level and comparable to the recombinant (brand-name) glucagon product.

Detection of innate immune response modulating impurities (IIRMI) in therapeutic peptides and proteins: Impact of excipients

Unintended immunogenicity can affect the safety and efficacy of therapeutic proteins and peptides, so accurate assessments of immunogenicity risk can aid in the selection, development, and regulation of biologics. Product- and process- related impurities can act as adjuvants that activate the local or systemic innate immune response increasing the likelihood of product immunogenicity. Thus, assessing whether products have innate immune response modulating impurities (IIRMI) is a key component of immunogenicity risk assessments. Identifying trace levels of individual IIRMI can be difficult and testing individually for all potential impurities is not feasible. Therefore, to mitigate the risk, cell-based assays that use human blood cells or monocyte-macrophage reporter cell lines are being developed to detect minute quantities of impurities capable of eliciting innate immune activation. As these are cell-based assays, there is concern that excipients could blunt the cell responses, masking the presence of immunogenic IIRMI. Here, we explore the impact of frequently used excipients (non-ionic detergents, sugars, amino acids, bulking agents) on the sensitivity of reporter cell lines (THP-1- and RAW-Blue cells) and fresh human blood cells to detect purified TLR agonists as model IIRMI. We show that while excipients do not modulate the innate immune response elicited by TLR agonists in vivo, they can impact on the sensitivity of cell-based IIRMI assays. Reduced sensitivity to detect LPS, FSL-1, and other model IIRMI was also evident when testing 3 different recombinant drug products, product A (a representative mAb), B (a representative growth factor), C (a representative peptide), and their corresponding formulations. These results indicate that product formulations need to be considered when developing and validating cell-based assays for assessing clinically relevant levels of IIRMI in therapeutic proteins. Optimization of reporter cells, culture conditions and drug product concentration appear to be critical to minimize the impact of excipients and attain sensitive and reproducible assays.