Glatiramer acetate contains polypeptides of varying lengths that fall within a defined molecular weight range; it is therefore a complex drug and not a simple small-molecule drug.
The UK patent for glatiramer acetate (GA) expired in May 2015; no generics have as yet been approved in the EU. The accompanying editorial notes that the European Medicines Agency required this equivalence trial to be conducted before considering registering Synthon’s generic glatiramer acetate.
The first generic version of GA was approved in the US in April 2015; this was a different product to that investigated in this study. The FDA required that the generic meet bioequivalence standards consistent with other parenteral generic drugs through the Abbreviated New Drug Application process; it did not however require the conduct of such a clinical trial to demonstrate equivalence.
The current study included a placebo arm, and one of the equivalence criteria was that both active treatment arms had to be superior to placebo in terms of the primary endpoint. The other criteria was that the ratio of generic drug to Copaxone® for the mean number of gadolinium-enhancing lesions and its 95% CI had to fall between predetermined equivalence margins (set at 0.727 to 1.375). Equivalence for efficacy was therefore demonstrated and adverse events were similar in the two active groups, suggesting the safety profiles are also similar.
The authors of the editorial say that neurologists should have confidence that GA generics approved by the US FDA and EMA will be as efficacious and safe as Copaxone®, and that their use in clinical practice will help to establish this.
Teva has recently launched a new branded glatiramer acetate (Copaxone, 40 mg) which is administered three times a week as opposed to once daily. Forthcoming generics will therefore need to compete with this formulation which may be preferred by patients due to its less frequent administration.