Plasma derivatives: new products and new approaches

Clinical Pharmacology Review of Plasma-derived and Recombinant Protein Products: CBER Experience and Perspectives on Model-Informed Drug Development

INTRODUCTION

Clinical pharmacology studies are one of the major types of regulatory data submitted for review of therapeutic proteins regulated by the Center for Biologics Evaluation and Research (CBER).

AIM

The primary objective of the current study is to provide an overview of the role of clinical pharmacology including pharmacokinetics (PK), pharmacodynamics (PD) and exposure-response analysis at CBER. Furthermore, we aim to provide a baseline estimate for the use of quantitative clinical pharmacology studies prior to implementation of FDA's model-informed drug development (MIDD) pilot programme.

METHODS

We survey original Biologics License Applications (BLAs) for plasma-derived and related recombinant therapeutic protein products approved by CBER/FDA (2008-2017).

RESULTS

There were 37 original BLAs that met our inclusion criteria, and 34 of these products (92%) contained human PK data as part of the biological licensing. The products were broadly classified as coagulation factors (54%), IgG and related proteins (24%), and other therapeutic proteins (22%). Coagulation factor VIII and IX products constitute 32% of the BLAs and indicated for treatment of haemophilia A and B, respectively. Twelve products (35%) used model-based approaches (population PK/PD and exposure-response). Over the past 5 years (2013 to 2017), there is a trend for increased application of MIDD approaches as compared to the previous cohort years (2008 to 2012).

CONCLUSION

In conclusion, clinical pharmacology has played a major role in regulatory review of plasma-derived products, and we expect that the application of quantitative methods will further evolve for these products under the FDA MIDD programme.

Fc fusion as a platform technology: potential for modulating immunogenicity

The platform technology of fragment crystallizable (Fc) fusion, in which the Fc region of an antibody is genetically linked to an active protein drug, is among the most successful of a new generation of bioengineering strategies. Immunogenicity is a critical safety concern in the development of any protein therapeutic. While the therapeutic goal of generating Fc-fusion proteins has been to extend half-life, there is a critical mass of literature from immunology indicating that appropriate design of the Fc component has the potential to engage the immune system for product-specific outcomes. In the context of Fc-fusion therapeutics, a review of progress in understanding Fc biology suggests the prospect of engineering products that have an extended half-life and are able to modulate the immune system.

The intron-22-inverted F8 locus permits factor VIII synthesis: explanation for low inhibitor risk and a role for pharmacogenomics

Intron-22-inversion patients express the entire Factor VIII (FVIII)-amino-acid sequence intracellularly as 2 non-secreted polypeptides and have a positive "intracellular (I)-FVIII-CRM" status. Mutations conferring a positive I-FVIII-CRM status are associated with low inhibitor risk and are pharmacogenetically relevant because inhibitor risk may be affected by the nature of the therapeutic FVIII-protein (tFVIII), the affinity of any tFVIII-derived foreign peptide (tFVIII-fp) for any HLA class-II isomer (HLA-II) comprising individual major histocompatibility complex (MHC) repertoires, and the stability of any tFVIII-fp/HLA-II complex. We hypothesize that mutations conferring a completely or substantially negative I-FVIII-CRM status are pharmacogenetically irrelevant because inhibitor risk is high with any tFVIII and individual MHC repertoire.

Building better drugs: developing and regulating engineered therapeutic proteins

Most native proteins do not make optimal drugs and thus a second- and third-generation of therapeutic proteins, which have been engineered to improve product attributes or to enhance process characteristics, are rapidly becoming the norm. There has been unprecedented progress, during the past decade, in the development of platform technologies that further these ends. Although the advantages of engineered therapeutic proteins are considerable, the alterations can affect the safety and efficacy of the drugs. We discuss both the key technological innovations with respect to engineered therapeutic proteins and advancements in the underlying basic science. The latter would permit the design of science-based criteria for the prediction and assessment of potential risks and the development of appropriate risk management plans. This in turn holds promise for more predictable criteria for the licensure of a class of products that are extremely challenging to develop but represent an increasingly important component of modern medical practice.