Biosimilar uptake in Japan has been a bit mixed, but according to experts the volume shares of biosimilars suggests it could be a key market in years to come.^[1] The Pharmaceuticals and Medical Devices Agency (PMDA), which is the agency responsible for approval of biologicals, approved the first biosimilar – Sandoz's recombinant human growth hormone somatropin – in 2009, and has approved eight biosimilars since. These products fall within the product classes of human growth hormone, granulocyte colony-stimulating factor, erythropoiesis stimulating agent, insulin and a tumor necrosis factor (TNF)-inhibitor.^[2]

There are a number of key factors that determine the uptake of biosimilars in Japan. One of which is how the product is used in Diagnostic Procedure Combination (DPC) hospitals and also the reimbursement costs under the medical care benefit program of the National Health Insurance scheme.^[3] To give an example of the variability in uptake, Filgrastim BS, first approved in Japan in 2012, achieved approximately a 45% volume share in two years. And earlier this year, Insulin glargine BS, achieved approximately a 9% volume share in the two months post launch.^[4] However, Infliximab BS only achieved a 1% volume share in the year post the 2014 launch.^[5]

With respect to pre-launch patent challenges, treatment in Japan is much like that in Europe.  Much like the European opposition system, biosimilar patent challengers in Japan prefer to utilize an invalidation procedure to patent litigation.^[6] There is a two-track system for patent resolution matters with the Board of Appeals of the Japan Patent Office (JPO) hearing trials for invalidation (post-grant patent proceedings), and the District Court hearing patent infringement actions.^[7] Unlike the US however, there is no suggestion or requirement for a pre-launch "patent dance." Perhaps the most significant difference between the US and Japan rests in that the PMDA will not approve generic drug or follow-on biological products before the composition of matter or second medical use patents expire.^[8] As a result, the Japanese legal system experiences less generic drug or follow-on biological products patent litigation.

With the pharmaceutical market in Japan set to rise from around $70 billion in 2016 to $72 billion by 2021, and the Japanese government promoting the use of generics as a cost-containment tool,^[9] Japan will likely be fertile ground for biosimilar manufacturers in the years to come.

_{[1] http://www.gabionline.net ; https://www.client-pharma.com}

_{[2] http://www.gabionline.net}

_{[3] https://www.client-pharma.com}

_{[4] Id.}

_{[5] Id.}

_{[6] http://gabi-journal.net}

_{[7] Kesan Jay P. A comparative appraisal of patent invalidation processes in Japan. IIP Bulletin 2004.}

_{[8] http://gabi-journal.net}

_{[9] https://www.dddmag.com}