Interim injunction to Novartis against Natco's use of Revolade patent

India's Delhi High Court recently granted an interlocutory injunction to Swiss pharma giant Novartis (NOVN: VX) against Natco Pharma’s (BSE: 524816) use of eltrombopag olamine (EO).

Natco had launched its own version of EO without obtaining a license from Novartis. Consequently, Novartis instituted a suit of infringement against Natco and also filed an application seeking interim injunction on Natco’s use of the EO patent.

The Delhi High Court restrained Natco from directly or indirectly dealing in the API. The patent was originally granted to SmithKline Beecham, which merged with Glaxo to become GlaxoSmithKline (LSE: GSK), on March 27, 2009.

Natco claimed a plea of invalidity of the EO patent under multiple subsections. It said the API provided therapeutic activity against thrombocytopenia is eltrombopag, marketed by Novartis as Revolade, and not EO. Revolade/Promacta generated global sales of $522 million for the third quarter of 2021.

The international filing date of the patent application for EO is May 21, 2003. The patent will remain active till May 21, 2023, by the virtue of Section 53 (1) of the Patent Act. After a trail of assignments, rights were assigned to Novartis Pharma AG in 2015. The EO is salt of eltrombopag (base) which is useful as an agonist of the TPO2 receptor, particularly in the treatment of thrombocytopenia.

To defend itself against the interim injunction application, Natco claimed a plea of invalidity of the EO patent under multiple subsections, and argued that the suit patent is covered under prior art IN 213176 (IN 176) which is a "compound and a pharmaceutical composition for use in enhancing platelet production." The filing date for IN 176 is May 24, 2001 and thus its term expired in May 2021.

To substantiate its point, Natco argued that in parallel patent prosecution proceedings in the European Union, USA and Canada, the eltrombopag patentee (GSK or Novartis) claimed EO as a part of eltrombopag patent. Natco then argued EO lacked an inventive step over the eltrombopeg patent.

The court opined that Natco has a heavy burden of proof to establish the EO patent’s invalidity. It ruled that Natco cannot "cherry pick substituents" from cited prior art and substitute them to arrive at suit patent.