Chugai Seiyaku Kabushiki Kaisha v. Controller Of Patents And Design

In the pharmaceutical world, inventing a new molecule is hard enough—but what about inventing a new *form* of an existing molecule? For one Japanese pharmaceutical company, this question became the difference between owning a patent and walking away empty-handed. The case of Chugai Seiyaku Kabushiki Kaisha versus the Controller of Patents and Design is a stark reminder that in the realm of drug patents, novelty alone is not always enough. The law demands something more: proof that the new form actually does something better.

Chugai Seiyaku Kabushiki Kaisha, a well-known pharmaceutical company, filed a patent application (No. 201617023236) seeking protection for a solid preparation containing Tofogliflozin in monohydrate crystal form. Tofogliflozin itself was not a brand-new invention—it was a known drug substance. What Chugai was attempting to patent was a specific crystalline form (the monohydrate) of that known substance, packaged as a solid preparation. The Patent Controller, however, was not convinced. The application was rejected on two grounds: first, that the invention lacked an inventive step, and second, that it fell foul of Section 3(d) of the Patents Act because it amounted to a new form of a known drug without demonstrating any enhanced efficacy.

Chugai pushed back, arguing that its monohydrate crystal form represented a genuine technical advancement worthy of patent protection. From their perspective, isolating a specific crystalline form of Tofogliflozin and formulating it as a solid preparation involved real innovation and should not be dismissed as a trivial variation. The Controller, on the other hand, stood firm on the legal framework. The core legal friction centered on Section 3(d) and its Explanation, which specifically targets the practice of evergreening—patenting minor tweaks to existing drugs without any real therapeutic benefit. The authorities countered that simply changing the physical form of a known substance, without proving it delivers superior results, does not meet the threshold of patentability. The question became: can a new crystal form of an existing drug be patented if it does not demonstrate enhanced therapeutic efficacy?

The court ruled in favor of the Controller, upholding the rejection of Chugai's patent application. The decision turned on the application of Section 3(d), read with its Explanation, which requires that new forms of known substances must demonstrate enhanced therapeutic efficacy to be considered patentable. Since Chugai's monohydrate crystal form of Tofogliflozin was treated as a new form of a known drug, the burden was on the applicant to show that this form offered improved efficacy. The court found that this requirement was not met. Additionally, the application was found to lack an inventive step. The outcome was a clear signal: the patent system will not reward mere reformulation without meaningful therapeutic improvement.

For pharmaceutical founders and IP professionals, this case delivers a critical lesson: when seeking patents for new forms, formulations, or crystalline structures of known drug substances, demonstrating enhanced therapeutic efficacy is not optional—it is a legal necessity under Section 3(d). It is not enough to show that a new form is novel or even technically clever. The application must clearly establish that the new form provides a meaningful therapeutic advantage over the existing substance. Before investing in patent applications for drug reformulations, innovators should rigorously evaluate whether their new form can demonstrate enhanced efficacy, and build their patent strategy around that evidence from day one.