In a recent case that we represented, the Supreme Court provided a relaxed standard for a crystalline form invention to account for technical difficulty in deriving the constitutional elements (“technical difficulty”) of the claimed crystalline form, like other types of inventions. This decision brings about a meaningful development in Korea as it would lower the standard for the inventive step of a crystalline form invention (Supreme Court Case No. 2018 Hu 10923, issued on March 31, 2022).
In Korea, since the Supreme Court established the standard for the inventive step of a crystalline form invention in Decision 2010 Hu 2865 in 2011, the inventive step of a crystalline form invention was recognized only if the crystalline form invention produces a qualitatively different or quantitatively remarkable effect in comparison to a known compound. That is, it was automatically assumed that there would be no technical difficulty since it was considered to be common in the art to examine the presence of a crystalline form and confirm its effect to improve the solubility or stability of a compound. However, it is extremely rare that a crystalline form invention produces a qualitatively different effect in comparison to a conventional known compound, and the standard for determining quantitative remarkability is also very strict. As such, it had been difficult for the inventive step of a new crystalline form of a known compound to be acknowledged in Korea. However, this standard is relaxed with this Supreme Court decision.
Case summary and Supreme Court’s determination
The claimed invention relates to Form I polymorph of tylosin. During prosecution, the KIPO issued a Final Rejection rejecting the invention for lacking an inventive step in view of the prior art document which discloses a tylosin compound. The IPTAB and the Patent Court both affirmed the final rejection denying the inventive step of Form I polymorph of tylosin.
However, the Supreme Court reversed the Patent Court’s decision and acknowledged an inventive step by recognizing the technical difficulty of a crystalline form invention for the reasons below:
- When determining the Inventive step of a crystalline form invention, it cannot be presumably concluded that there is no technical difficulty of a crystalline form invention just because polymorph screening is ordinarily conducted, and it is necessary to consider the technical difficulty of constructing a specific crystalline form.
- When determining the technical difficulty of a crystalline form invention, the following factors should be considered: 1) whether the polymorphism of the prior art compound was known or expected, 2) whether the prior art discloses any teachings, suggestions or motivations to conceive the claimed crystalline form, 3) whether the claimed crystalline form is within the scope of the polymorphs that would have been readily screened via conventional polymorphic screening of the prior art compound, and 4) whether the claimed crystalline form produces an advantageous effect which could not be anticipated.
- In view of the above factors, the prior art merely discloses a tylosin compound and does not specify a crystalline form. Furthermore, there was no disclosure to determine that it was known in the art that tylosin had various polymorphs at the timing of the filing of the subject case. In addition, it is not obvious that the claimed Form I polymorph of tylosin can be easily derived only by a common polymorphic screening method. Further, in view of the specification of the subject case, the Form I polymorph of tylosin is thermodynamically stable and has low hygroscopicity, and it would be difficult to conclude that such an effect could be anticipated from the prior art. Therefore, it would have been technically difficult to derive the constitutional elements of the Form I polymorph of tylosin.
The Supreme Court determined in the decision that it cannot be presumably concluded that there is no technical difficulty of a crystalline form invention just because polymorph screening is ordinarily conducted, and the inventive step of a crystalline form invention may be recognized based on the technical difficulty, i.e., under the same standard as other inventions. Furthermore, the Supreme Court provided specific standards for determining the technical difficulty of a crystalline form invention. Accordingly, contrary to the previous practice, it would become easier for the inventive step of a crystalline form invention to be acknowledged by demonstrating that it is difficult to derive the claimed crystalline form or that the claimed crystalline form produces an advantageous effect.
This decision appears to have the same purpose as Decision Hu 10609 in 3032 in which the Supreme Court ruled that the technical difficulty must be considered when determining the inventive step of a selection invention (please see our summer newsletter of 2021). With this Supreme Courts’ decision, the same standard for the inventive step can be applied to inventions of a special form in the pharmaceutical compound field, such as a selection invention and a crystalline form invention. Thus, it is expected for follow-up research and patent applications for these inventions to be actively increased.