UK Court of Appeal Judgment on Dapagliflozin Patent

UK Court of Appeal Judgment: Dapagliflozin Patent

In a recent landmark judgment, the UK Court of Appeal upheld the High Court’s April 2025 decision invalidating the UK equivalent patent of EP1506211B1 (expired on May 14, 2023) for Dapagliflozin and its associated Supplementary Protection Certificate (SPC) (Expiry Date: May 13/14, 2028).

The case marks a significant development in UK patent law, particularly in the pharmaceutical sector, and reinforces strict standards for plausibility and inventive step in patent applications.

Background of the Case

AstraZeneca (AZ) had appealed against the High Court’s ruling, which declared the Dapagliflozin patent invalid. The Court of Appeal dismissed the appeal, affirming that the patent failed on both lack of inventive step and insufficiency.

The dispute involved AstraZeneca and generics manufacturers: Teva, Viatris, and Glenmark.

Product: Forxiga / Farxiga

Precedents Referenced

  • Generics (UK) Ltd v Warner-Lambert Co LLC [2018]
  • Sandoz v Bristol Myers Squibb (Apixaban)

These cases clarify the plausibility requirement in UK patent law.

Why Was the Patent Revoked?

  • Lacked plausibility: Failed to convincingly demonstrate Dapagliflozin as an SGLT2 inhibitor or its usefulness for diabetes treatment.
  • Arbitrary selection from prior art: Offered no technical contribution over WO 01/27128 A1 (“WO 128”).

The Plausibility Standard: Bare Assertion vs. Contribution to the Art

The Court stressed that a bare assertion of a technical effect is insufficient. For a chemical compound patent to be valid:

The specification must make it plausible, in light of a skilled person’s common general knowledge, that the compound has the stated utility.

In this case:

  • The patent disclosed in-vitro assays for multiple SGLT2 inhibitors but provided no experimental data specifically supporting Dapagliflozin.
  • This was deemed speculation, not a technical contribution to the field.

Can Post-Filing Data Help?

Yes, post-filing data can be used to defend plausibility, but it cannot replace adequate disclosure in the original specification.

Arbitrary Selection vs. Inventive Selection

The judgment clarified:

  • Merely choosing a compound from a known genus is not inventive unless it brings a technical advance.
  • An inventive selection requires:
    • A different or improved property compared to prior disclosures.
    • Plausible support for that improvement in the patent specification.

In AstraZeneca’s case:

  • They argued that if prior art lacked plausibility for the genus, a later patent could make the same assertion plausible for a selected compound.
  • The Court rejected this, holding that only a genuine technical contribution makes such a selection inventive.

Key Takeaways

  • Plausibility is non-negotiable: Provide enough experimental evidence or credible reasoning in the specification to support the claimed utility.
  • Avoid bare assertions: Numerical data, in-vitro results, or robust scientific reasoning strengthen plausibility.
  • Inventive step requires contribution: The compound must demonstrate a real, supported technical advantage if selecting from prior art.
  • Post-filing data is supplementary: It cannot fill a disclosure gap in the original filing.

Impact on Pharmaceutical Patents in the UK

This decision signals that UK courts will strictly apply plausibility and inventive step requirements, particularly in life sciences patents. It serves as a cautionary tale for drug developers and IP strategists:

  • Early patent filings must balance speed and sufficient disclosure.
  • Drafting strategies should anticipate plausibility challenges from both examiners and competitors.