Bioequivalence decision for nanoparticular iron complex drugs for parenteral administration based on their disposition

Regulatory Science Approach in Pharmaceutical Development of Follow-On Versions of Non-Biological Complex Drug Products

Scientific and technological breakthroughs in the field of Nanotechnology have been a driving force throughout the development and approval of Non-Biological Complex Drugs (NBCDs). However, the fast-growing expansion of NBCDs and the emergence of their follow-on versions have brought with them several scientific, technological, and regulatory challenges. The definition of NBCDs is still not officially recognized by the regulatory authorities, and there is no dedicated regulatory pathway addressing the particular features of NBCDs and their follow-on versions. The lack of clear and consistent regulatory guidance documents in this field, as well as, the inconsistency across different regulatory agencies, impact negatively on the acceptance and enormous potential of these drug products. Patient access to high-quality NBCDs follow-on versions may be compromised by regulatory uncertainty resulting from the use of different regulatory approaches across the globe, as well as within the same class of products. Accordingly, there is a real need to develop a specific regulatory pathway compliant with the complexity of NBCDs and their follow-on versions or, alternatively, make better use of available regulatory pathways. The main goal of the review is to deeply investigate and provide a critical overview of the regulatory landscape of NBCDs and follow-on versions currently adopted by the regulatory authorities. The dissemination of knowledge and discussion in this field can contribute to clarifying regulations, policies, and regulatory approaches to complex generics, thereby filling regulatory and scientific gaps in the establishment of therapeutic equivalence.

Regulatory challenges of nanomedicines and their follow-on versions: A generic or similar approach?

Nanomedicines and follow-on versions (also called nanosimilars in the EU) have been on the market partially for decades although without recognition of their nano properties in the beginning; a substantial number is in clinical development. Nanomedicines are typically synthetic and belong to the non-biological complex drugs. They show a high variability in form, structure, and size. Additionally large molecule biologics show nano-characteristics meaning nano-dimension in size (1-100 nm) or specific properties related to these dimensions. The high complexity of nanomedicines with their heterogeneous structures do not allow a full physicochemical quality characterization, challenging the regulatory evaluation especially for follow-on versions upon comparison with the reference product. The generic paradigm with the sameness approach for quality and bioequivalence in blood plasma is not appropriate for nanomedicines where a similar approach is needed. After experiencing non-equivalence of authorized parenteral colloidal iron follow-on versions, EMA and FDA issued reflection papers and draft guidances for industry to present their current thinking on the evaluation of such complex products. A stepwise approach to evaluate the extent of similarity, from quality, including critical quality attributes (CQA) and assessment of nano properties, to a non-clinical biodistribution assay, required in the the EU but not in the US, and to clinical evaluation makes sense. The cumulated totality of evidence for the authorization of nanomedicine follow-on versions goes case-by-case. Interchangeability, or substitutability, is a challenge. However, a defined or even harmonized approval pathway for these follow-versions is still missing and causes potential differences in approval. To progress, a science-based discussion platform among stakeholders and experts in the field is necessary. An agenda has been agreed [5], namely CQA assessment, publication of scientific and clinical findings, consensus on nomenclature and labelling, and regulatory actions on substandard complex drug products. Consensus created in a public private approach will support progress towards a defined and harmonized regulatory pathway for nanomedicines and their follow-on versions. This will provide drug innovation but also larger access to follow-on versions of nanomedicines, both a benefit for the patient.