Secrecy about manufacturing processes poses a potentially significant deterrent to the development of biosimilars.  Although it is not always easy to get hold of samples of brand-name drugs [2], once obtained, small molecule drugs can be fully characterized by analysing the end products, and any of a number of simple manufacturing processes will result in an approvable generic drug product. In contrast, biologicals are often complex and cannot be fully characterized in this way.

Whereas small molecule pharmaceutical firms rely almost entirely on patent protection and exclusivity to preserve their market power, biologicals makers also rely on secrecy about their manufacturing processes. The implication is that even if originator firms provide samples of their products to biosimilar manufacturers, secrecy about the manufacturing process impedes development of biosimilars after a patent has expired.

Manufacturing of biologicals is more challenging than for traditional small molecule drugs. Even minor changes in manufacturing process can cause significant changes in efficacy or immunogenicity [3]. In fact, it is often said that ‘the process is the product’ when it comes to biologicals [4, 5].

Conflict of interest
Disclosure forms provided by the author [1] are available at NEJM.org.

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References
1.  Frank RG. Friction in the path to use of biosimilar drugs. N Engl J Med. 2018;378(9):791-3.
2.  GaBI Online - Generics and Biosimilars Initiative. REMS issues come under FDA spotlight [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 May 11]. Available from: www.gabionline.net/Generics/General/REMS-issues-come-under-FDA-spotlight
3.  GaBI Online - Generics and Biosimilars Initiative. Small molecule versus biological drugs [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 May 11]. Available from: www.gabionline.net/Biosimilars/Research/Small-molecule-versus-biological-drugs
4.  GaBI Online - Generics and Biosimilars Initiative. Why is “the process the product” for biosimilars? [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 May 11]. Available from: www.gabionline.net/Biosimilars/Research/Why-is-the-process-the-product-for-biosimilars
5.  GaBI Online - Generics and Biosimilars Initiative. Biologicals: characteristics that make them unique and special [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 May 11]. Available from: www.gabionline.net/Biosimilars/Research/Biologicals-characteristics-that-make-them-unique-and-special

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