Equivalence of glatiramer acetate products: challenges in assessing pharmaceutical equivalence and critical clinical performance attributes

A pragmatic regulatory approach for complex generics through the U.S. FDA 505(j) or 505(b)(2) approval pathways

The diverse nature of complex drug products poses challenges for the development of regulatory guidelines for generic versions. While complexity is not new in medicines, the technical capacity to measure and analyze data has increased. This requires a determination of which measurements and studies are relevant to demonstrate therapeutic equivalence. This paper describes the views of the NBCD Working Group and provides pragmatic solutions for approving complex generics by making best use of existing U.S. Food and Drug Administration's abbreviated approval pathways 505(j) and 505(b)(2). We argue that decisions on the appropriateness of submitting a 505(j) or 505(b)(2) application can build on the FDA's complex drug product classification as well as the FDA's much applauded guidance document for determining whether to submit an ANDA or a 505(b)(2) application. We hope that this paper contributes to the discussions to increase the clarity of regulatory approaches for complex generics, as well as the predictability for complex generic drug developers, to facilitate access to much‐needed complex generics and to promote the sustainability of the healthcare system.

Application of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization for enhanced peptide mapping analysis of non-biological complex drug glatiramer acetate using liquid chromatography/electrospray ionization collision-induced dissociation high-resolution mass spectrometry

RATIONALE

Glatiramer acetate (GA) (Copaxone®) is a non-biological complex drug (NBCD) comprising random-sequence polymer chains of four amino acids (MW ~ 5-9 kDa) with unknown structure. The characterization of NBCDs by reversed-phase liquid chromatography/mass spectrometry (RPLC/MS) peptide mapping is often impeded by insufficient separation and/or low sensitivity. To overcome this issue, pre-column derivatization of GA peptide digest was used to improve RPLC/MS detectability and to generate a comprehensive peptide profile.

METHODS

Amino groups of peptides generated by trypsin digestion of GA were derivatized using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) reagent. The derivatized mixture of random-sequence peptides was analyzed by liquid chromatography/positive-mode electrospray ionization collision-induced dissociation high-resolution mass spectrometry (RPLC/ESI-CID-HRMS/MS). Data-independent LC/MS^E mode was used for data acquisition.

RESULTS

The derivatization of the GA peptide mixture increased the detectability of RPLC/ESI-CID-HRMS/MS analysis. The efficacy of the procedure was demonstrated by using selected peptides related to different polymeric chain origins. The resultant peptides were derivatized in a predictable manner giving a minimum of side products. The reproducibility of the developed method was demonstrated by comparing peptide elution profiles derived from six Copaxone® lots.

CONCLUSIONS

Application of the AQC pre-column derivatization provides a framework that could be used as an attractive approach for monitoring the quality and characterization of NBCD products in the pharmaceutical industry.

Enduring Clinical Value of Copaxone® (Glatiramer Acetate) in Multiple Sclerosis after 20 Years of Use

Multiple sclerosis (MS) is a chronic progressive neurodegenerative demyelinating disease affecting the central nervous system. Glatiramer acetate (GA; Copaxone®) was the first disease-modifying treatment (DMT) for MS successfully tested in humans (1977) and was approved by the US Food and Drug Administration in December 1996. Since then, there have been numerous developments in the MS field: advances in neuroimaging allowing more rapid and accurate diagnosis; the availability of a range of DMTs including immunosuppressant monoclonal antibodies and oral agents; a more holistic approach to treatment by multidisciplinary teams; and an improved awareness of the need to consider a patient's preferences and patient-reported outcomes such as quality of life. The use of GA has endured throughout these advances. The purpose of this article is to provide an overview of the important developments in the MS field during the 20 years since GA was approved and to review clinical data for GA in MS, with the aim of understanding the continued and widespread use of GA. Both drug-related (efficacy versus side-effect profile and monitoring requirements) and patient factors (preferences regarding mode of administration and possible pregnancy) will be explored.