Another US patent litigation win for Orexo AB’s ZUBSOLV®

Orexo’s ZUBSOLV® was approved for the treatment of opioid dependence in 2013, which drug is covered by, amongst others, US patent nos. 9,439,900 (‘900) and 11,020,387 (‘387), both of which are listed in the FDA's publication, Approved Drug Products with Therapeutic Equivalence Evaluations (the “Orange Book”).

Sun filed an Abbreviated New Drug Application (ANDA) for a generic version of ZUBSOLV® before expiration of the ZUBSOLV® patents listed in the Orange Book, with Sun submitting a paragraph IV certification asserting that the patents are invalid, unenforceable, and/or will not be infringed by the activities in Sun’s ANDA. Orexo initiated litigation in September 2020 as a response to Sun’s ANDA filing.

Unlike the first generic challenge, that came from Actavis and focussed its invalidity claim on obviousness, Sun also alleged that the patents are invalid on grounds of indefiniteness, written description and enablement. The Court ruled against Sun on all grounds and in favour of Orexo on their claim of infringement, with Sun infringing on claims of both ‘900 and ‘387. This decision means that Sun is prohibited from launching its generic version of Zubsolv® until September 2032. The issuance of the decision caused Orexo’s share price to rally by almost 80%.

Sun have appealed the decision, but Nikolaj Sørensen, President and CEO of Orexo, remains optimistic about the outcome and stated in a recent press release:

"The District Court’s decision was very well motivated, and it clearly outlines the extensive flaws in Sun’s claims regarding the patents’ validity and infringement issue. We remain very confident about the strength of the Zubsolv patent portfolio and believe that the Court of Appeals will reach the same conclusion."

Stephen McNeeney, the Potter Clarkson Partner that has been responsible for Orexo’s patent portfolio and strategy for over 20 years, and who drafted and was coordinated prosecution of ZUBSOLV patents on a worldwide basis, comments:

"From our perspective, it is good to see that, for a second time, the US courts have upheld the validity of our client’s ZUBSOLV patents. Recent trends have shown that, on top of more “traditional” lines of attack, such as lack of novelty and/or inventive step, generics are increasingly focussing their invalidity attacks on the more “formal” grounds of indefiniteness, written description and enablement. In order to avoid US patents being vulnerable to attack on these grounds, which are unrectifiable irrespective of how inventive the ultimate product that is covered is, it is vital that patent applications are well drafted and thought-through at the time of filing."

Potter Clarkson has been working with SMEs in the pharma/biotech space for many years, and helping an increasing number with litigation strategies, whether they intend to commercialise themselves in the US, or find a partner to do that. If you need further advice in this regard, please do reach out to a Potter Clarkson representative on our ANDA team.