CA-2025-001040 - [2025] EWCA Civ 903

WO 128

The judge set out the disclosure of WO 128 alongside that of the Patent at [145]-[184]. Comparison of the two documents shows that the text of the Patent was largely copied from that of WO 128, but omits a substantial amount of material contained in WO 128. The principal difference between the two documents is that, as explained in paragraph 5 above, WO 128 discloses and claims three classes of what are said to be SGLT2 inhibitors. The narrowest class is represented by Formula IB shown below.

In addition, WO 128 describes 15 “Working Examples” in which the preparation and characterisation of specific compounds are described in detail. It also gives a more summary description of the preparation and characterisation of a further 65 Examples. One of the Working Examples described in WO 128 is Example 12. This describes the preparation and characterisation of the compound shown below.

This compound differs from dapagliflozin only in that the group at the R⁴ position is -OMe (-OCH₃ or methoxy) whereas it is -OEt (-OC₂H₅ or ethoxy) in dapagliflozin.

So far as the assay is concerned, the content of the two documents is the same: a passage at page 52 line 9 to page 53 line 12 of WO 128 is identical to the specification of the Patent at [0114]-[0116]. Like the Patent, WO 128 contains no results from the assay.

The final point to note is that WO 128 states, while acknowledging prior art, at page 7 lines 14-19:

“Other disclosures and publications which disclose SGLT2 inhibitors include the following:

K. Tsujihara et al, Chem. Pharm Bull.44, 1177-1180 (1996)

M. Hongu et al, Chem. Pharm Bull. 46, 22-23 (1998)

M. Hongu et al, Chem. Pharm Bull. 46, 1545-1555 (1998)

Oku et al, Diabetes, 48, 1794-1800 (1999)”.

These four papers all emanated from Tanabe Seiyaku.