Compositional differences between Copaxone and Glatopa are reflected in altered immunomodulation ex vivo in a mouse model

Abstract

Copaxone (glatiramer acetate, GA), a structurally and compositionally complex polypeptide nonbiological drug, is an effective treatment for multiple sclerosis, with a well-established favorable safety profile. The short antigenic polypeptide sequences comprising therapeutically active epitopes in GA cannot be deciphered with state-of-the-art methods; and GA has no measurable pharmacokinetic profile and no validated pharmacodynamic markers. The study reported herein describes the use of orthogonal standard and high-resolution physicochemical and biological tests to characterize GA and a U.S. Food and Drug Administration-approved generic version of GA, Glatopa (USA-FoGA). While similarities were observed with low-resolution or destructive tests, differences between GA and USA-FoGA were measured with high-resolution methods applied to an intact mixture, including variations in surface charge and a unique, high-molecular-weight, hydrophobic polypeptide population observed only in some USA-FoGA lots. Consistent with published reports that modifications in physicochemical attributes alter immune-related processes, genome-wide expression profiles of ex vivo activated splenocytes from mice immunized with either GA or USA-FoGA showed that 7-11% of modulated genes were differentially expressed and enriched for immune-related pathways. Thus, differences between USA-FoGA and GA may include variations in antigenic epitopes that differentially activate immune responses. We propose that the assays reported herein should be considered during the regulatory assessment process for nonbiological complex drugs such as GA.

Physicochemical, biological, functional and toxicological characterization of the European follow-on glatiramer acetate product as compared with Copaxone

“…The method is based on a nondestructive separation of the polypeptide mixture into subgroups according to their average overall charge, ie affinity to the negatively charged stationary phase of a separating column. Further details on the methods have been provided previously [ 13 ].…”

“…Gene expression profiling was applied for three lots of Synthon EU FOGA (Germany Clift lots 1503711E and 1503713B; Slovakia Remurel lot 1601434B) and three lots of Copaxone (P63256, P63265, P63275) in two complementary biological assays. These two experiments, validated previously [ 12 , 13 , 16 ], model the molecular effects of treatment on antigen presenting cells (APCs) and T cells, which represent the two cell types that, along with the antigen (GA or FOGA, respectively), form the “ immunological triad ” that is critical to the mechanism of action of Copaxone [ 18 ]. Furthermore, the T-cell model system was designed to identify molecular differences associated with switching, relevant for the consideration of safety and immunogenicity in the context of (repeated) substitution in real-world settings.…”

“…Given the aforementioned characterization challenges, a battery of peptide/protein-appropriate evaluation methods was employed by Teva to examine the compositional characteristics of glatiramer acetate in Copaxone and FOGA lots, as well as their associated functional ramifications. This battery, which includes quality control release tests used routinely for release of Copaxone lots, high resolution physicochemical tests [ [7] , [8] , [9] , [10] , [11] ], biological characterization tests, as well as gene expression studies and a rat toxicity study, has been applied to other FOGA products marketed globally, and the findings of these analyses have been published [ [12] , [13] , [14] , [15] , [16] , [17] ]. Consistently, the collected results of these analyses highlight the difficulties and challenges in manufacturing a complex peptide mixture such as GA and demonstrate that many of the FOGA lots produced by different manufacturers globally do not contain the same active substance as Copaxone, as differences and similarities are demonstrated in different assays.…”

“…Consistently, the collected results of these analyses highlight the difficulties and challenges in manufacturing a complex peptide mixture such as GA and demonstrate that many of the FOGA lots produced by different manufacturers globally do not contain the same active substance as Copaxone, as differences and similarities are demonstrated in different assays. Furthermore, differences in physicochemical and functional attributes were detected for all FOGAs tested to-date [ [12] , [13] , [14] , [15] , [16] , [17] ], which remain to be qualified with respect to their impact on clinical immunogenicity and long-term safety and efficacy, as well as (repeated) substitutability in real-world settings (the term “substitution” herein refers to the practice of dispensing one medicine instead of another at the pharmacy level without the consultation of a physician).…”

“…The present study sought to determine the comparability of the active ingredient in Copaxone to that in the Synthon EU FOGA, employing a battery of physicochemical and biological assays reported previously [ [12] , [13] , [14] , [15] , [16] , [17] ]. To this end, six lots of Synthon's FOGA purchased in four different European countries were compared with Copaxone specifications or inherent variability ranges, utilizing a total of fourteen methods.…”