On 24 March 2025, a single judge of the Delhi High Court refused to grant an interim injunction against Natco Pharma for manufacturing a generic version of F Hoffmann-La Roche’s risdiplam – the only oral drug available in India for the treatment of spinal muscular atrophy (CS(COMM) 567/2024 & IA 33088/2024, IA 44310/2024, IA 44384/2024).
On appeal, a Delhi High Court division bench restrained Natco from launching its generic version until further hearing.
Case background
Roche sought an interim injunction against Natco to prevent infringement of its Indian species patent (IN334397) covering the compound risdiplam, which is marketed globally under the brand name Evrysdi. Roche also holds two related patents: US9969754 (the US species patent corresponding to the Indian one) and US9586955 (the US genus patent corresponding to WO 2013/119916 A2 – the international genus patent related to risdiplam).
Roche argued that Natco effectively admitted infringement by stating that it was preparing to launch risdiplam, maintaining that the Indian species patent could not be anticipated nor rendered obvious based on the disclosure in WO’916 because risdiplam was only broadly covered but not specifically claimed. Roche also highlighted that even after the consideration of WO’916, the foreign patents corresponding to the Indian species patent remained unchallenged in more than 60 jurisdictions.
Natco countered that Roche’s case amounted to patent evergreening, arguing that both WO’916 and the Indian species patent covered the same compounds for treating spinal muscular atrophy. It argued that if Roche could enforce its genus patent abroad, the same patent should serve as prior art to invalidate the disputed patent in India. Natco also noted that Roche obtained a patent term extension for the US genus patent by admitting that risdiplam was a new drug discovered under that patent, contradicting its arguments in India.
Based on these arguments, the single judge denied the grant of an interim injunction to Roche.
Key observations
Anticipation by prior publication
Natco argued that risdiplam was already disclosed in genus patent US’955 and stood anticipated. Roche however argued that while it was covered, risdiplam was not “specifically claimed” in the genus patent. To determine the credibility of Natco’s challenge, the court relied on Bayer Healthcare v Natco (CS(COMM) 567/2024) and held that disclosure can be implicit or inherent, and there is no stringent rule that it ought to be explicit in nature to invalidate a patent.
The court also referenced Roche’s contradictory stance in a suit filed against Natco in the United States for manufacturing risdiplam and infringing its US genus patent. Here, Roche claimed that Natco infringed US’955. However, in India, it asserted that risdiplam was only covered – not disclosed – in the international genus patent and Natco was infringing the Indian counterpart.
Since both the genus and species patents had common inventors, the single judge applied the test for considering anticipation by prior publication and obviousness from the point of view of a person in the know – as per the court’s findings in AstraZeneca & Another v Intas Pharmaceutical (2021). It concluded that a person in the know could anticipate risdiplam from the genus patent and Natco had raised a credible challenge to the suit patent’s validity on the grounds of anticipation by prior publication.
Obviousness
The court observed that the key difference between the suit patent and genus patent WO’916 is that nitrogen replaced a carbon-hydrogen group in the former. Since both nitrogen and carbon-hydrogen are bioisosteres, a substitution to obtain risdiplam would be obvious to a person in the know, making the suit patent vulnerable to revocation.
Public interest
Three factors are assessed before granting an interim injunction:
- prima facie case;
- irreparable loss; and
- balance of convenience.
Turning its attention to the second and third factors, the court noted that Roche imports risdiplam into India, while Natco intends to manufacture the drug in India and make it available at a price that is 80% to 90% lower than that of Roche. It was noted that Roche’s Patient Assistance Program benefitted only a small fraction of enrolled patients and raised the question of adequate accessibility for a larger number of spinal muscular atrophy patients outside the programme. Thus, the balance of convenience for grant of injunction weighed in favour of Natco; if Roche succeeded post-trial, it could be compensated with damages.
The court also considered the issue of public interest, noting that the availability of a lifesaving drug to the public at very economical and competitive prices was a material factor.
The road ahead
The single judge upheld Natco’s challenge to the disputed patent’s validity and refused to block it from manufacturing a generic version of risdiplam. However, Roche filed an appeal, and the division bench restrained Natco from launching its generic version until further hearing.
The issues of coverage and disclosure of genus and species patents in pharmaceuticals is controversial in India. While the judgment is comprehensive and seemingly aligned with public interest, there is still a lack of clear and comprehensive guidance on the application of the credible challenge test, particularly in relation to the nuanced and technical evaluation of inventive step. It is hoped that more clarity will come following full trial of this matter.
This is an Insight article, written by a selected partner as part of IAM’s co-published content. Read more on Insight