Examination Guidelines for Patent Applications Relating
to Pharmaceutical Inventions in the Japan Patent Office｜IP Laws & Practices

6. Combination DrugsGeneral
- A new combination of known drugs may involve inventive step if the combination attains an unexpected remarkable effect.

NOTE: With regard to combination drugs, the Japan Patent Office states that a new combination of known drugs may involve inventive step if the combination attains an unexpected remarkable effect.

6-1.Example (Combination Drugs)Inventive Step: YES
[Claim]
An anticancer drug comprising compound A and compound B in combination.
[Prior Art]:
Both compounds A and B were known to have anticancer activities.
[Remarkable Effect: YES]
The specification provides the pharmacological test data to demonstrate a synergistic effect by the combination. Therefore, the remarkable effect is acknowledged.

NOTE: As to the remarkableness, the patent office acknowledges a synergistic effect to be remarkable. The synergistic effect must be clearly demonstrated in the specification as filed by means of pharmacological test data. Also refer to "Enablement/Written Description Requirements".

6-2.Example (Combination Drugs)Inventive Step: NO
[Claim]
A liquid composition for treating diarrhea comprising bacteria strain YY and dietary fiber wherein the ratio of the bacteria to dietary fiber is 1x10-6 - 1x10-8 cells: 1-30 g.
[Prior Art]
Both strain YY and dietary fiber were known to have anti-diarrhea effect.
[Remarkable Effect: NO]
The specification does not demonstrate any synergistic effect and the effect is considered as additive. No remarkable effect is acknowledged.

NOTE: However, if the effect is not synergistic but just additive, the claims would be rejected as not involving inventive step.

6-3.Example (Combination Drugs)Inventive Step: YES
[Claim]
A pharmaceutical composition for treating diabetes comprising compound A and compound B in combination.
[Prior Art]
Both compounds A and B were known as anti-diabetes agents. Compound A was known to increase body weight due to the side effect.
[Remarkable Effect: YES]
The specification provides the pharmacological test data and demonstrates that compound B decreased the side effect of compound A, which is unpredictable from the prior art. Therefore, remarkable effect is acknowledged.

NOTE: However, if the effect is not synergistic but just additive, the claims would be rejected as not involving inventive step.

6-4.Example (Combination Drugs)Inventive Step: NO
[Claims]
A pharmaceutical composition for treating patients with cancer comprising compound A and compound B in combination.
[Prior Art]
Compound A is a known anti-cancer agent having vomiting side effect. Compound B is anti-emetics.
[Remarkable effect: NO]
The specification demonstrates that the combination can significantly reduce the vomiting-side effect. However, the effect is foreseeable. No unexpected remarkable effect is acknowledged.

NOTE: However, even if the side effect is reduced in the combination drug, the combination would not be inventive insofar as the effect is foreseeable.