December, 2016｜News Letter

1. Should “Buffering Agent” in Claim be Interpreted as being Limited to “Added Oxalic Acid” Only or as Including “Dissociated Oxalic Acid”?

Nippon Kayaku Co., Ltd. v. Debiopharm International S.A., Case No. 2016 (Ne) 10031 (Decision rendered on December 8, 2016)

The former Patentee, Sanofi-Aventis, obtained a patent relating to an oxaliplatin solution formulation in 2009, and transferred the patent to Debiopharm in 2014. Debiopharm filed an infringement suit based on the patent against Nippon Kayaku (NK) with the Tokyo District Court in 2015. The Tokyo District Court decided that NK infringed the Debiopharm’s patent in 2016. NK appealed against the Tokyo District Court's decision to the IPHC in 2016.

Corrected Claim 1 of the Debiopharm's patent at issue claims as follows:
A stable oxaliplatin solution formulation comprising oxaliplatin, an effective stabilizing amount of a buffering agent and a pharmaceutically acceptable carrier, wherein the pharmaceutically acceptable carrier is water and the buffering agent is oxalic acid or an alkali metal salt thereof, and
1) wherein the amount of buffering agent is a molar concentration in the range of from (a) 5 x 10^-5 M to 1 x 10^-2 M, (b) 5 x 10^-5 M to 5 x 10^-3 M, (c) 5 x 10^-5 M to 2 x 10^-3 M, (d) 1 x 10^-4 M to 2 x 10^-3 M or (e) 1 x 10^-4 M to 5 x 10^-4 M, with a pH in the range of 4.5 to 6; or 2) wherein the amount of buffering agent is a molar concentration in the range of from 5 x 10^-5 M to 1 x 10^-4 M.

One of the main issues in this case related to whether “buffering agent” in the claim at issue should be interpreted as being limited to oxalic acid externally added to the oxaliplatin solution formulation (“added oxalic acid”) only or as including, besides the added oxalic acid, oxalic acid formed by dissociation of oxaliplatin in the formulation (“dissociated oxalic acid”). The IPHC answered to the issue as follows:

In the decision of the 1st instance, the Tokyo District Court interpreted “buffering agent” in the claim at issue as including not only added oxalic acid, but also dissociated oxalic acid, and decided that NK infringed the patent at issue since the accused NK’s product contained dissociated oxalic acid in the claimed range, although it contained no added oxalic acid.

However, having reviewed the claim of the patent at issue, the specification thereof including the definition of the term “buffering agent” and the examples, and the relationship between the claimed invention at issue and prior art in detail, the IPHC interpreted the term “buffering agent” as being limited to added oxalic acid only for the following reasons:

(1) According to the recitation of the Claims, the present invention is an invention relating to an "oxaliplatin solution formulation" comprising" (i) "oxaliplatin", (ii) a "buffering agent" which is "oxalic acid or an alkali metal salt thereof", and a "carrier" which is water. Therefore, it is natural to understand that, in the present invention, each of the elements (i) to (iii) mentioned above can be grasped as an independent element composing the formulation. However, "dissociated oxalic acid" is necessarily formed in an oxaliplatin solution by reacting "oxaliplatin" with "water" and thereby naturally decomposing "oxaliplatin", and will not be present in the first place unless "oxaliplatin" and "water" are mixed together. Therefore, it is unreasonable to understand that such "dissociated oxalic acid" is an element independent of "oxaliplatin" or "water" composing an "oxaliplatin solution formulation".
(2) An "agent" used in a term "buffering agent" means in general "preparing various medicines, or such medicines". Therefore, according to such general meaning, "dissociated oxalic acid" which seems inconceivable to be "prepared" is not a "buffering agent".
(3) The specification of the present application provides a definition of a term "buffering agent" which reads, "The term of the buffering agent as used herein means any acidic or basic agent which is capable of stabilizing oxaliplatin solutions and thereby preventing or retarding the generation of unwanted impurities such as diaquo DACH platin and diaquo DACH platin dimer". Dissociated oxalic acid is formed along with diaquo DACH platin by a portion of oxaliplatin in an aqueous solution being decomposed. In other words, dissociated oxalic acid is at most an element constituting a state of equilibrium naturally occurring as a result of a reaction between oxaliplatin and water in an oxaliplatin aqueous solution. Therefore, it is unreasonable to understand that such dissociated oxalic acid is a substance that serves the function to prevent or retard the formation of diaquo DACH platin and the like in a reaction leading to the state of equilibrium.
(4) Examples of the specification of the present application only disclose examples of externally adding a buffering agent. Further, tables of ingredients relating to the examples only show weights and molar concentrations derived therefrom of oxalic acid or oxalic sodium added in the production process. Therefore, in the specification of the present application, there is no trace of a dissociated oxalic acid being considered regarding the amount (molar concentration) of a "buffering agent", and the amount (molar concentration) of dissociated oxalic acid being added is exclusively considered.

Conclusively, the IPHC found that NK did not infringe the Debiopharm’s patent and overturned the Tokyo District Court's decision.

An appeal to the Supreme Court was filed against this decision, and thus the decision is NOT final and binding.

K&P’s CommentsThe above decision teaches that, even though “added oxalic acid” and “dissociated oxalic acid” are identical as compounds, a claimed term defined by a kind of functional expression, such as a “buffering agent”, should be interpreted as covering only the matter serving the function, such as “added oxalic acid”.

In December 2016, the IPHC handed down 16 decisions including the above case on patent, and overturned the previous decisions in 6 cases.

In December 2016, the IPHC handed down 2 decisions on trademark, and overturned the previous decision in 1 case.

In December 2016, the IPHC handed down 8 decisions on industrial design, and overturned all of the previous decisions.

Meanwhile, regarding “Debiopharm International S.A. v. Towa Pharmaceutical Co., Ltd.”, Case No. 2016 (Ne) 10046 (Decision rendered on January 20, 2017) presented in our Special News Flash e-mailed on January 23, 2017, we confirmed that an appeal to the Supreme Court was filed against the decision, and thus the decision is not final and binding.